Vicar’s assistant is after power? Correct! (8)
I believe the answer is:
accurate
'correct' is the definition.
(associated in meaning)
'vicar's assistant is after power?' is the wordplay.
'vicar's assistant' becomes 'curate' (I've seen this before).
'is after' means one lot of letters go next to another.
'power?' becomes 'AC' (AC is an example).
'curate' put after 'ac' is 'ACCURATE'.
(Other definitions for accurate that I've seen before include "Totally correct" , "True!" , "telling it like it is" , "Precise and exact (8)" , "Precise, correct" .)