Pictures of US agents holding rebellious men (6)
I believe the answer is:
cinema
'pictures' is the definition.
(I've seen this before)
'us agents holding rebellious men' is the wordplay.
'us agents' becomes 'cia' (CIA, Central Intelligence Agency).
'holding' means one lot of letters goes inside another.
'rebellious' is an anagram indicator.
'men' anagrammed gives 'nem'.
'cia' enclosing 'nem' is 'CINEMA'.
'of' is the link.
(Other definitions for cinema that I've seen before include "Film theatre" , "Local form of language" , "Motion pictures" , "The big screen" , "Picture house" .)