Leader of rogue state is party animal (5)
I believe the answer is:
raver
'party animal' is the definition.
(I've seen this before)
'leader of rogue state' is the wordplay.
'leader of' indicates taking the first letters.
'state' becomes 'aver' (both can mean to declare).
The initial letter of 'rogue' is 'r'.
'r'+'aver'='RAVER'
'is' acts as a link.
(Other definitions for raver that I've seen before include "one talking incoherently" , "Uninhibited person" , "Dedicated partygoer" , "Party animal" , "Madman" .)