Not returning with certain bald patch (7)
I believe the answer is:
tonsure
'bald patch' is the definition.
'tonsure' can be an answer for 'patch' (I have seen 'bare patch' mean 'tonsure' so perhaps 'patch' could also mean 'tonsure'). I am unsure of the 'bald' bit.
'not returning with certain' is the wordplay.
'returning' says the letters should be written backwards.
'with' says to put letters next to each other.
'certain' becomes 'sure' (synonyms).
'not' backwards is 'ton'.
'ton'+'sure'='TONSURE'
Can you help me to learn more?
(Other definitions for tonsure that I've seen before include "Monk's haircut" , "Monk's hair style" , "Monk's hairstyle" , "Shearing ?" , "Monk's bald spot" .)