Trap poor Ann’s caught in before (7)
I believe the answer is:
ensnare
'trap' is the definition.
(to ensnare is to trap or capture)
'poor ann's caught in before' is the wordplay.
'poor' indicates anagramming the letters.
'caught in' means one lot of letters goes inside another.
'before' becomes 'ere' (poetic term for 'before').
'anns' anagrammed gives 'nsna'.
'nsna' going inside 'ere' is 'ENSNARE'.
(Other definitions for ensnare that I've seen before include "Ambush" , "Catch as if in a trap or net" , "Capture, trap" , "Ecstatic expression of feeling" .)