A poem sounds due (3)
I believe the answer is:
ode
'a poem' is the definition.
(ode is a type of poem)
'sounds due' is the wordplay.
'sounds' indicates a 'sounds like' (homophone) clue.
'due' becomes 'owed' (synonyms).
'owed' sounds like 'ODE'.
(Other definitions for ode that I've seen before include "Poem expressing noble feelings" , "Verse form" , "poetry" , "Lyric poem" , "Literary work" .)