Contrast poem arc badly (7)
I believe the answer is:
compare
'contrast' is the definition.
(I've seen this before)
'poem arc badly' is the wordplay.
'badly' indicates anagramming the letters (letters in the wrong order).
'poem'+'arc'='poemarc'
'poemarc' is an anagram of 'COMPARE'.
(Other definitions for compare that I've seen before include "Contrast - liken" , "what discriminators do" , "Look at differences and similarities between (things)" , "Represent as similar; sounds like emcee" .)