1: Stiff spelunker swallowed plug (7)
2: Point back to itself. (5)
3: Herb talked about the fourth dimension (5)
4: Celebration geared for retirement (6,5)
5: Choose to take the top off (3)
6: Old English mixed into edited cryptic shows exceptional maturity (9)
7: Boo, in case it's the end of the train (7)
8: Italian gentlemen's token or piece of silver (7)
13: For Proust, life's purpose springs from remembrance of a torn desire (6,5)
15: Believer in esoteric powers is joining quasi-religious group in October (9)
17: Church organ initially secures selections (7)
18: Aerial worker Anne on the way up (7)
20: City Auto Club's closing, mired in debt (7)
23: Sensible and articulate (5)
25: About....about right? Wrong! (3)