Trump's behind troubles and torments (7)
I believe the answer is:
assails
'torments' is the definition.
(assail can mean to torment or attack)
'trump's behind troubles' is the wordplay.
'trump's behind' becomes 'ass' (US term for your behind).
'troubles' becomes 'ails' (as verb).
'ass'+'ails'='ASSAILS'
'and' acts as a link.
(Other definitions for assails that I've seen before include "Attacks" , "storms" .)