A revolutionary can be a pain (4)

I believe the answer is:

ache

'be a pain' is the definition.
(I've seen this before)

'a revolutionary' is the wordplay.
'revolutionary' becomes 'che' (Che Guevara the Marxist revolutionary).
'a'+'che'='ACHE'

'can' acts as a link.

(Other definitions for ache that I've seen before include "Dull prolonged pain" , "Each (anag.)" , "burn" , "Persistent dull pain" , "Dull steady pain" .)

I've seen this clue in The Guardian and the Sydney Morning Herald.

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