Dorothy's dog eating mother's fruit (6)
I believe the answer is:
tomato
'fruit' is the definition.
(I've seen this before)
'dorothy's dog eating mother's' is the wordplay.
'dorothy's dog' becomes 'toto' (Dorothy's dog in The Wizard of Oz).
'eating' is an insertion indicator.
'mother' becomes 'ma' (ma is a kind of mother).
'toto' going around 'ma' is 'TOMATO'.
(Other definitions for tomato that I've seen before include "Part of a BLT sandwich" , "Fruit-vegetable" , "A motto turned out to be fruit or veg" , "Love apple (archaic)" , "that's suitable to eat" .)