Work with engineer in cupola (4)
I believe the answer is:
dome
'cupola' is the definition.
(thesaurus)
'work with engineer' is the wordplay.
'work' becomes 'do' ('do work' can be a synonym of 'work'**).
'with' means one lot of letters go next to another.
'engineer' becomes 'me' (mechanical engineer).
'do'+'me'='DOME'
'in' is the link.
(Other definitions for dome that I've seen before include "Cupola - millennium building" , "Old cathedral" , "A stately building" , "Curved roof" , "Rounded roof with circular base" .)