A jar containing rice for the most part, or fruit (7)
I believe the answer is:
apricot
'fruit' is the definition.
(apricot is a kind of fruit)
'a jar containing rice for the most part' is the wordplay.
'jar' becomes 'pot' (I've seen this in other clues**).
'containing' is an insertion indicator.
'for the most part' means to remove the last letter.
'rice' with its last letter removed is 'ric'.
'pot' enclosing 'ric' is 'pricot'.
'a'+'pricot'='APRICOT'
'or' acts as a link.
(Other definitions for apricot that I've seen before include "tree" , "Yellow fruit" , "Rip coat (anag) - fruit" , "Fruit from a tropic" , "shade" .)