Nick's not at church (5)
I believe the answer is:
notch
'nick's' is the definition.
(both can mean a small cut or impression)
'not at church' is the wordplay.
'at' is a charade indicator (letters next to each other).
'church' becomes 'ch' (common abbreviation).
'not'+'ch'='NOTCH'
(Other definitions for notch that I've seen before include "Make the cut" , "V-shaped nick" , "Small V-shaped cut or indentation" , "Salad plant, garnish" , "Dent" .)