Poem of the wooden horse (3)
I believe the answer is:
ode
'poem' is the definition.
(ode is a type of poem)
'of the wooden horse' is the wordplay.
'of' says the answer is hidden in the clue.
'ODE' can be found hidden inside '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" .)