Morsel for a squirrel (5)
I believe the answer is:
acorn
'morsel for a squirrel' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for acorn that I've seen before include "oak's fruit" , "Fruit of the oak tree" , "Source of a great oak" , "Dirt on a liquid surface" , "From which a "tall oak" may grow" .)