Nick's not going to church (5)
I believe the answer is:
notch
'nick's' is the definition.
(both can mean a small cut or impression)
'not going to church' is the wordplay.
'going to' says to put letters next to each other.
'church' becomes 'ch' (abbreviation on maps etc).
'not'+'ch'='NOTCH'
(Other definitions for notch that I've seen before include "Cleft" , "Incision; indentation" , "small score?" , "Dent" , "Nick made in something as a record" .)