Figure of speech seen in poet's last line (5)
I believe the answer is:
'figure of speech' is the definition.
(I've seen this before)
'poet's last line' is the wordplay.
'last' says to take the final letters.
'line' becomes 'rope' (rope is a kind of line**).
The last letter of 'poet' is 't'.
'seen in' is the link.
(Other definitions for trope that I've seen before include "Word or expression used in a figurative way" , "Recurrent theme, motif" , "figuratively speaking" , "Word used in a figurative sense" , "Figurative use of a word or expression; motif" .)