Tops of unripe mangoes and melons I used to create something savoury (5)
I believe the answer is:
umami
'something savoury' is the definition.
(umami is a savoury taste)
'tops of unripe mangoes and melons i' is the wordplay.
'tops of' indicates taking the first letters.
The initial letters of 'unripe mangoes and melons' is 'umam'.
'umam'+'i'='UMAMI'
'used to create' acts as a link.
(Other definitions for umami that I've seen before include "Fifth flavour" , "Japanese word for pleasant savoury taste" , "acquired taste perhaps" , "Savoury flavour" , "Newly discovered taste" .)