Motto may be 'to consume a type of fruit' (6)
I believe the answer is:
tomato
'type of fruit' is the definition.
'motto may be to consume a' is the wordplay.
'may be' indicates an anagram.
'to consume' is an insertion indicator.
'motto' with letters rearranged gives 'tomto'.
'tomto' enclosing 'a' is 'TOMATO'.
(Other definitions for tomato that I've seen before include "A motto turned out to be fruit/veg" , "Red fruit eaten as veg" , "Type of sauce" , "A glossy red fruit eaten as a vegetable" , "A motto turned out to be fruit or veg" .)