Singers, choosy (not half!) I recognise at first (5)
I believe the answer is:
choir
'singers' is the definition.
(group of singers)
'choosy not half i recognise at first' is the wordplay.
'not half' indicates taking half.
'at first' indicates taking the first letters.
The first letter of 'recognise' is 'r'.
'choosy' halved is 'cho'.
'cho'+'i'+'r'='CHOIR'
(Other definitions for choir that I've seen before include "They sing" , "Group of singers, often in church" , "Organised group of singers" , "set of singers" , "Singers in harmony" .)