Old lady and man in assembly (6)
I believe the answer is:
making
'assembly' is the definition.
(thesaurus)
'old lady and man' is the wordplay.
'old lady' becomes 'ma' (both can informally mean mother).
'and' says to put letters next to each other.
'man' becomes 'king' (man can mean a chess piece).
'ma'+'king'='MAKING'
'in' is the link.
(Other definitions for making that I've seen before include "Fabricating" , "Creating" , "Manufacturing" , "production" .)