Dresses Frenchman as revolutionary (11)
I believe the answer is:
robespierre
'revolutionary' is the definition.
(French revolutionary Maximilien Robespierre)
'dresses frenchman' is the wordplay.
'dresses' becomes 'robes' (robing is a kind of dressing).
'frenchman' becomes 'pierre' (common French name).
'robes'+'pierre'='ROBESPIERRE'
'as' acts as a link.
(Other definitions for robespierre that I've seen before include "old revolutionary" , "French revolutionary who was guillotined" , "leading figure in French history" , "French Jacobin leader, guillotined in 1794" , "Revolutionary leader" .)