Officer organised a ride behind prison (9)
I believe the answer is:
brigadier
'officer' is the definition.
(I know that brigadier is a type of officer)
'organised a ride behind prison' is the wordplay.
'organised' indicates an anagram.
'behind' is a charade indicator (letters next to each other).
'prison' becomes 'brig' (I've seen this before).
'a'+'ride'='aride'
'aride' is an anagram of 'adier'.
'adier' after 'brig' is 'BRIGADIER'.
(Other definitions for brigadier that I've seen before include "Air bridge over to the military officer" , "Army rank" , "Military leader" , "Officer in charge of army unit, part of division" , "High-ranking army officer" .)