Fancy Conservative party (5)
I believe the answer is:
crave
'fancy' is the definition.
(thesaurus)
'conservative party' is the wordplay.
'conservative' becomes 'c' (abbreviation commonly used in UK politics).
'party' becomes 'rave' (I've seen this before).
'c'+'rave'='CRAVE'
(Other definitions for crave that I've seen before include "Beg; long for" , "Fairly sizeable" , "Have strong urge" , "Beseech" , "Really want" .)