Calls back about the man's varnish (7)
I believe the answer is:
shellac
'varnish' is the definition.
(I know that shellac is a type of varnish)
'calls back about the man's' is the wordplay.
'back' says the letters should be written backwards.
'about' indicates putting letters inside.
'the man' becomes 'he' (pronoun for a man).
'calls' reversed gives 'sllac'.
'sllac' going around 'he' is 'SHELLAC'.
(Other definitions for shellac that I've seen before include "coat" , "Resin in flakes, used to making varnish" , "(it's in old records)" , "Sort of resin" , "Take a shine to" .)