The gentleman who took part in the uprising (3)
I believe the answer is:
sir
'the gentleman' is the definition.
(I've seen this before)
'took part in the uprising' is the wordplay.
I cannot really see how this works, but
'part' could be 'si' (si is a kind of part) and 'si' is found in the answer.
A single letter 'r' remains which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
'who' is the link.
Can you help me to learn more?
(Other definitions for sir that I've seen before include "... ___ John Major" , "Title given to 10 Across" , "Polite or formal address to male" , "Respectful address for a man" , "Knight's title" .)