Poem that's outstanding, reportedly (3)
I believe the answer is:
ode
'poem' is the definition.
(ode is a kind of poem)
'outstanding reportedly' is the wordplay.
'outstanding' becomes 'owed' (as in an outstanding debt).
'reportedly' shows a homophone (sound like).
'owed' sounds like 'ODE'.
'that's' acts as a link.
(Other definitions for ode that I've seen before include "Literary work" , "(Railway)system" , "A poem celebrating person or event" , "Lines" , "Sung poem" .)