Pain for a guerrilla leader (4)
I believe the answer is:
ache
'pain' is the definition.
(ache is a kind of pain)
'a guerrilla leader' is the wordplay.
'guerrilla leader' becomes 'che' (guerrilla revolutionary Che Guevara).
'a'+'che'='ACHE'
'for' acts as a link.
(Other definitions for ache that I've seen before include "Pine" , "Long ? pain" , "Similar" , "Continuous hurt" , "Shakespearean character" .)