A lot of seedy old fruit (5)
I believe the answer is:
mango
'fruit' is the definition.
(type of fruit)
'a lot of seedy old' is the wordplay.
'a lot of' means to remove the last letter (most of the word but not all of it).
'seedy' becomes 'mangy' (mangy can mean seedy or squalid).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'mangy' with its last letter removed is 'mang'.
'mang'+'o'='MANGO'
(Other definitions for mango that I've seen before include "product" , "Yellow-fleshed fruit" , "Type of fruit" , "Tropical fruit, its pickle" , "Ovoid edible fruit" .)