Duke's boots (11)
I believe the answer is:
wellingtons
'boots' is the definition.
(Wellington is an example)
'duke's' is the wordplay.
I cannot quite see how this works, but
'duke' could be 'ellington' (I've seen this before) and 'ellington' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for wellingtons that I've seen before include "Gum boots" , "Gumboots" , "Waterproof boots" .)