Potter character in audition? (3)
I believe the answer is:
cue
'potter' is the definition.
(a cue pots balls in snooker etc)
'character in audition?' is the wordplay.
'character' becomes 'q'.
'in audition?' shows a homophone (sound like) (audition can mean hearing).
'q' is a homophone of 'CUE'.
(Other definitions for cue that I've seen before include "Actor's prompt" , "Actor's line to remind another" , "Tapering stick used by snooker player" , "Billiards stick" , "Rod used in billiards" .)