He often resorts to a piece in colour (7)
I believe the answer is:
habitue
'he often resorts' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'a piece in colour' is the wordplay.
'a piece' becomes 'abit' (synonyms).
'in' indicates putting letters inside.
'colour' becomes 'hue' (I've seen this before).
'abit' placed within 'hue' is 'HABITUE'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for habitue that I've seen before include "Regular visitor (to place)" , "Constant visitor" , "One of the regulars" , "Regular customer" , "One who visits a place frequently 97)" .)