Sound of sheep eating grandma's fruit (6)
I believe the answer is:
banana
'fruit' is the definition.
(type of fruit)
'sound of sheep eating grandma's' is the wordplay.
'sound of sheep' becomes 'baa' (sound made by a sheep).
'eating' means one lot of letters goes inside another.
'grandma' becomes 'nan' (I've seen this before).
'baa' enclosing 'nan' is 'BANANA'.
(Other definitions for banana that I've seen before include "Sub-tropical fruit" , "Yellow fruit with slippery skin" , "Fruit that comes in a bunch" , "that may be unzipped" , "Curved yellow fruit" .)