Former soldiers caught on wrong side driven out! (9)
I believe the answer is:
exorcised
'driven out' is the definition.
'former soldiers caught on wrong side' is the wordplay.
'former' becomes 'ex'.
'soldiers' becomes 'or' (Other Rank).
'caught' becomes 'c' (cricket abbreviation**).
'on' indicates putting letters inside.
'wrong' indicates anagramming the letters.
'side' with letters rearranged gives 'ised'.
'c' going within 'ised' is 'cised'.
'ex'+'or'+'cised'='EXORCISED'
(Other definitions for exorcised that I've seen before include "Cast out" , "Driven away" , "Removed spirit" , "Delivered from the influence of an evil spirit" .)