Poem of the wooden horse (3)
I believe the answer is:
ode
'poem' is the definition.
(ode is a kind of poem)
'of the wooden horse' is the wordplay.
'of' indicates a hidden word.
'ODE' is hidden in the letters of 'wooden horse'.
(Other definitions for ode that I've seen before include "Verse form" , "poetry" , "- - to a 12 Urn" , "Lines" , "Poem in praise of doe" .)