Heroic Latvian revolutionary (7)
I believe the answer is:
valiant
'heroic' is the definition.
(I've seen this in another clue)
'latvian revolutionary' is the wordplay.
'revolutionary' indicates an anagram.
'latvian' with letters rearranged gives 'VALIANT'.
(Other definitions for valiant that I've seen before include "Heroic" , "Stout-hearted" , "Showing courage" , "Brave in battle" , "Dauntless" .)