Degenerate English leader of Fascist party (6)
I believe the answer is:
effete
'degenerate' is the definition.
(thesaurus)
'english leader of fascist party' is the wordplay.
'english' becomes 'e' (abbreviation).
'leader of' says to take the initial letters.
'party' becomes 'fete' (I've seen this before).
The first letter of 'fascist' is 'f'.
'e'+'f'+'fete'='EFFETE'
(Other definitions for effete that I've seen before include "Over-refined, pretentious" , "Enfeebled" , "Worn-out, decadent" , "Feeble, having lost vitatlity" , "Weak, effeminate" .)