Duke avoids fools (7)
I believe the answer is:
deludes
'fools' is the definition.
(I've seen this in another clue)
'duke avoids' is the wordplay.
'duke' becomes 'd' (abbreviation).
'avoids' becomes 'eludes' (eluding is a kind of avoiding).
'd'+'eludes'='DELUDES'
(Other definitions for deludes that I've seen before include "dupes" , "Deceives (as to truth)" , "Fools" , "Tricks" .)