Duke featured in old English verse (3)
I believe the answer is:
ode
'verse' is the definition.
(ode is a type of poem or verse)
'duke featured in old english' is the wordplay.
'duke' becomes 'd' (abbreviation).
'featured in' means one lot of letters goes inside another.
'old english' becomes 'OE'.
'd' going within 'oe' is 'ODE'.
(Other definitions for ode that I've seen before include "Lyric poem" , "Sung poem" , "Lines" , "Verse form" , "Poetic composition" .)