Couple with brief moment in Italian cathedral (5)
I believe the answer is:
duomo
'italian cathedral' is the definition.
(Italian term for a cathedral)
'couple with brief moment' is the wordplay.
'couple' becomes 'duo' (two people).
'with' means one lot of letters go next to another.
'brief moment' becomes 'mo' (as in 'just a mo'; 'brief' indicates an abbreviation).
'duo'+'mo'='DUOMO'
'in' acts as a link.
(Other definitions for duomo that I've seen before include "Italian cathedral" , "foreign cathedral" , "Large church" , "Roman church" .)