Builder thus punching worker? (5)
I believe the answer is:
mason
'builder' is the definition.
(I've seen this before)
'thus punching worker?' is the wordplay.
'thus' becomes 'so' (synonyms).
'punching' is an insertion indicator (I've seen this in other clues).
'worker?' becomes 'man' (man is a kind of worker).
'so' inserted within 'man' is 'MASON'.
(Other definitions for mason that I've seen before include "Jewish comedian" , "A skilled worker in stone" , "one called Perry?" , "Builder in stone" , "secretive lodger!" .)