A comedian should have this hat I'm in, gran admits (6)
I believe the answer is:
timing
'a comedian should have this' is the definition.
(comedy requires good timing)
'hat i'm in gran admits' is the wordplay.
'admits' indicates the answer is hidden within the clue.
'TIMING' is hidden within 'hat im in gran'.
(Other definitions for timing that I've seen before include "Supposedly, the secret of great comedy" , "Comedic skill" , "Temporal co-ordination" , "Entrails used as food" , "Regulating" .)