Taste that's not sweet, sour, bitter or salty (5)
I believe the answer is:
umami
'taste that's not sweet sour bitter or salty' 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 "meaty taste" , "Savoury taste sensation produced by glutamates - I, a mum (anag)" , "Japanese word for pleasant savoury taste" , "Newly discovered taste" , "acquired taste perhaps" .)