Fruit, mostly tropical, mixed up (7)
I believe the answer is:
apricot
'fruit' is the definition.
(type of fruit)
'mostly tropical mixed up' is the wordplay.
'mostly' means to remove the last letter (most but not all of the word).
'mixed up' indicates an anagram.
'tropical' with its last letter removed is 'tropica'.
'tropica' anagrammed gives 'APRICOT'.
(Other definitions for apricot that I've seen before include "Juicy stone-fruit, orange-pink when ripe" , "Fruit resembling a peach" , "tree" , "A fruit-tree" , "Soft, peach-like fruit" .)