Fish sauce taste (5)
I believe the answer is:
umami
'fish sauce taste' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for umami that I've seen before include "Savoury flavour" , "Savoury taste sensation produced by glutamates - I, a mum (anag)" , "Japanese word for pleasant savoury taste" , "Newly discovered taste" , "acquired taste perhaps" .)