As usual, the definitions are underlined (except in double definition and cryptic definition clues).
1. Son of Susie? (5) = ISSUE
An anagram that doesn't really have an anagram indicator, although it could be argued that the question mark serves that purpose. I don't think it's fair, though. The anagram fodder is Susie. ISSUE is defined here as progeny/children (hence son).
4. Constitutional nature's changed (7) = SAUNTER
Changed is the anagram indicator, and nature's is the fodder. A constitutional is a rather old-fashioned term for a regular walk (good for the constitution, don'tcha know).
8. Dad's silent partner (3) = MUM
Cute double definition clue. Mum is Dad's partner, but it's also a word that means to be quiet.
9. An order without speech (9) = TRAPPISTS
Cryptic definition. The Trappist monks are an order of monks where speech is not allowed most of the time.
10. Rushed to fire rifle (7) = RANSACK
Charade clue. Rushed = RAN. Fire = SACK (as in "Fire all the staff!"). Rifle is the definition, meaning to rummage through stuff (not a gun).
11. Having no occupation (5) = EMPTY
Cryptic definition, occupation doesn't mean a job here, but the state of being occupied or full.
13. Not put out when one did some hoarding (4,2) = LAID IN
I don't think the definition of this clue is correctly matched to the answer. Surely hoarding should clue LAYING IN, and LAID IN should be clued as hoarded. Cryptic definition? Not sure about this one. I guess the opposite (not) of LAID OUT (put out) is LAID IN?
15. Unions strangely in agreement (6) = UNISON
Anagram clue, indicated by strangely. Unions is the fodder.
18. Ascended a small hill to the north (5) = RISEN
Charade clue. A small hill = RISE + N (North).
19. Thicken stew in cook's place (7) = KITCHEN
An anagram (stew) of thicken.
21. Betrayed — like a bride in church maybe (5,4) = GIVEN AWAY
Double definition. If someone gives you away, you may either be a bride on her wedding day, or a plotter being betrayed!
23. A bishop's responsibility is to make observations (3) = SEE
Double definition: a bishop's responsibility (Dictionary definition: the place in which a cathedral church stands, identified as the seat of authority of a bishop or archbishop) and to make observations.
24. He looks after someone's wardrobe and sideboard (7) = DRESSER
Double definition - a dresser is both a piece of furniture, and a man who helps actors get dressed and looks after theatrical costumes.
25. Very small driving area close to New York (5) = TEENY
Charade clue - very small is the definition. You can get to it by putting TEE (driving area) next to NY (New York).
1. Dissolute, but I'm getting the message (7) = IMMORAL
Charade clue, IM (I'm) + MORAL (the message, as in the message of a story).
2. I can't mess around with the meanings of words (9) = SEMANTICS
Anagram of I can't mess, indicated by around.
3. Speechless player (5) = EXTRA
Cryptic definition — a player / actor in a movie or play who doesn't say anything is an extra.
4. Is lazy, resulting in a deficiency on board (6) = SLACKS
Container clue. On board = SS (for steamship). A deficiency = LACK. Put LACK inside SS.
5. Numerous men put in place around the East (7) = IMMENSE
Anagram and container. Anagram of men put.
6. Sit up when it is abbreviated (3) = TIS
Cute little reversal - sit written up (backwards) is TIS, an abbreviation of it is.
7. Out of practice but try us anyway (5) = RUSTY
Anagram (anyway) of try us.
12. Assembled the pots as speedily as possible (9) = POSTHASTE
Anagram, indicated by assembled. The fodder is the pots as.
14. Games period (7) = INNINGS
Cryptic definition. Innings are a set period in a game of cricket.
16. Community centre for retired ladies (7) = NUNNERY
Cryptic definition. Retired here means 'retired/retreated from everyday life', not retired from work, so retired ladies can be nuns.
17. A joint stake (6) = SKEWER
Cryptic definition. A skewer is something you might use to stake a roast joint (eg a leg of lamb)?
18. Stiff clothes I'd put on (5) = RIGID
Charade clue - clothes RIG + ID (I'd).
20. Test the patience of a good man at a meeting (5) = TRYST
Charade clue. Test the patience = TRY + a good man = ST (for saint).
22. Contend it's a quarter past six (3) = VIE
Charade clue. Put one of the quarters (of the compass, ie N, S, E, or W) after VI (Roman numeral for six).
Let me know if you have any better thoughts on these clues :)