Outstanding poem read out loud (4)
I believe the answer is:
owed
'outstanding' is the definition.
(as in an outstanding debt)
'poem read out loud' is the wordplay.
'poem' becomes 'ode' (ode is a type of poem).
'read out loud' shows a homophone (sound like).
'ode' is a homophone of 'OWED'.
(Other definitions for owed that I've seen before include "In debt to" , "(Sum) due for payment" , "Was indebted" , "to be paid" , "Outstanding" .)