In being on loan, half the team have a moan (6)
I believe the answer is:
lament
'a moan' is the definition.
(thesaurus)
'in being on loan half the team' is the wordplay.
'in' is an insertion indicator.
'being on loan half' becomes 'la' (I can't justify this - if you can you should believe this answer much more).
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'team' becomes 'men' (group of people).
'la'+'t'='lat'
'lat' going around 'men' is 'LAMENT'.
'have' is the link.
Can you help me to learn more?
(Other definitions for lament that I've seen before include "Dirge; bewail" , "Show of sorrow" , "Song expressing grief" , "Wail" , "Mourn, express regret" .)