A mostly forthright party delivering fruit (7)
I believe the answer is:
avocado
'fruit' is the definition.
(avocado is a kind of fruit)
'a mostly forthright party' is the wordplay.
'mostly' means to remove the last letter.
'forthright' becomes 'vocal' (I've seen this before).
'party' becomes 'do' (do is a kind of party).
'vocal' with its final letter taken away is 'voca'.
'a'+'voca'+'do'='AVOCADO'
'delivering' acts as a link.
(Other definitions for avocado that I've seen before include "Tropical salad ingredient" , "Ingredient of guacamole" , "Shade of green" , "Green-fleshed fruit" , "one's stoned?" .)