Craftsman's mother and child (5)
I believe the answer is:
mason
'craftsman's' is the definition.
(mason is a kind of craftsman)
'mother and child' is the wordplay.
'mother' becomes 'ma' (ma can mean mother).
'and' means one lot of letters go next to another.
'child' becomes 'son' (male child).
'ma'+'son'='MASON'
(Other definitions for mason that I've seen before include "One works with stone or brick" , "Secret society member" , "One is skilful with stone" , "figure in lodge" , "Craftsman working in stone" .)