Jenny over trouble in attack (6)
I believe the answer is:
assail
'attack' is the definition.
(I know that attack can be written as assail)
'jenny over trouble in' is the wordplay.
'jenny' becomes 'ass' (jenny is a female ass).
'over' is a reversal indicator.
'trouble' becomes 'ail' (synonyms).
'in' indicates putting letters inside.
'ass' written backwards gives 'ssa'.
'ssa' put inside 'ail' is 'ASSAIL'.
(Other definitions for assail that I've seen before include "Aggressively attack" , "Make violent attack on" , "Criticize" , "Go for" , "Attack, lash out" .)