Gentleman incarcerated in prison following revolution (3)
I believe the answer is:
sir
'gentleman' is the definition.
(a man may be addressed as sir)
'in prison following revolution' is the wordplay.
'in' indicates the answer is hidden within the clue.
'revolution' says the letters should be written backwards.
'ris' can be found hidden inside 'prison following'.
'ris' reversed gives 'SIR'.
'incarcerated' is the link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for sir that I've seen before include "Form of address for a knight" , "Noble title of undesirable kind" , "... ___ John Major" , "Honorary male title" , "Formal term of address" .)