Couples with quiet manners (5)
I believe the answer is:
pairs
'couples' is the definition.
(I know this)
'with quiet manners' is the wordplay.
'with' means one lot of letters go next to another.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'manners' becomes 'airs' (air is a kind of manner).
'p' next to 'airs' is 'PAIRS'.
(Other definitions for pairs that I've seen before include "Couples" , "Duos" , "golfing matches" .)