Wants to include creature (3)
I believe the answer is:
ant
'creature' is the definition.
(ant is a kind of creature)
'wants to include' is the wordplay.
'to include' says the answer is hidden in the clue.
'ANT' can be found hidden inside 'wants'.
(Other definitions for ant that I've seen before include "Emmet or pismire" , "Small social insect" , "Termite" , "One working hard" , "Dec's long-time partner" .)