Bar, with five couples, disheartened older male singer (12)
I believe the answer is:
countertenor
'male singer' is the definition.
(type of male singing voice)
'bar with five couples disheartened older' is the wordplay.
'bar' becomes 'counter' (as in the counter of a pub or bar).
'with' says to put letters next to each other.
'five couples' becomes 'ten' (five lots of two).
'disheartened' suggests removing the centre (the middle or heart is removed).
'older' with its centre taken out is 'or'.
'counter'+'ten'+'or'='COUNTERTENOR'
(Other definitions for countertenor that I've seen before include "Singer" , "Highest male singing voice" , "Adult male with an alto voice" , "he'll sing" , "being highly vocal" .)