Opposed to one piece of poetry (6)
I believe the answer is:
averse
'opposed' is the definition.
(synonyms)
'one piece of poetry' is the wordplay.
'one' becomes 'a'.
'piece of poetry' becomes 'verse' (I've seen this before).
'a'+'verse'='AVERSE'
'to' acts as a link.
(Other definitions for averse that I've seen before include "Having a strong opposition (to)" , "Loath, reluctant" , "'Opposed, disinclined (6)'" , "Antipathetic" , "Not in favour of" .)