State support part of UK rejected (5)
I believe the answer is:
india
'state' is the definition.
(India is an example)
'support part of uk rejected' is the wordplay.
'support' becomes 'aid' ('aid' can be a synonym of 'support'**).
'part of uk' becomes 'ni' (Northern Ireland).
'rejected' is a reversal indicator.
'aid'+'ni'='aidni'
'aidni' in reverse letter order is 'INDIA'.
(Other definitions for india that I've seen before include "Type of paper, rubber etc" , "Populous Asian country" , "Large Asian republic" , "where to ring for help?" , "I identified on radio" .)