Craftsman working by degrees (5)
I believe the answer is:
mason
'craftsman' is the definition.
(mason is a kind of craftsman)
'working by degrees' is the wordplay.
'working' becomes 'on'.
'by' means one lot of letters go next to another.
'degrees' becomes 'mas' (MA is an example**).
'on' put after 'mas' is 'MASON'.
(Other definitions for mason that I've seen before include "Craftsperson who works with stone or brick" , "Jewish comedian" , "Construction industry employee" , "One going to work in building" , "One is skilful with stone" .)