Carelessly lose pay in Pacific island group (9)
I believe the answer is:
polynesia
'pacific island group' is the definition.
(I've seen this before)
'carelessly lose pay in' is the wordplay.
'carelessly' indicates anagramming the letters.
'lose'+'pay'+'in'='losepayin'
'losepayin' anagrammed gives 'POLYNESIA'.
(Other definitions for polynesia that I've seen before include "Pacific region?" , "Pacific island group" , "Antipodeans around here" , "The islands of eastern Oceania" , "Extensive group of Pacific islands" .)