Desperately want to be in Conservative Party? (5)
I believe the answer is:
crave
'desperately want' is the definition.
(I've seen this in another clue)
'conservative party?' is the wordplay.
'conservative' becomes 'C' (UK political abbreviation).
'party?' becomes 'rave' (type of dance party).
'c'+'rave'='CRAVE'
'to be in' is the link.
(Other definitions for crave that I've seen before include "Feel a powerful desire for (something)" , "Long for, desire" , "Powerfully desire" , "need, desperately" , "Have strong desire for, or beg as for mercy" .)