I’m a Greek character picking up taste (5)
I believe the answer is:
umami
'taste' is the definition.
(I've seen this before)
'i'm a greek character picking up' is the wordplay.
'greek character' becomes 'mu' (letter from the Greek alphabet).
'picking up' says the letters should be written backwards (in a down clue, letters go up).
'im'+'a'+'mu'='imamu'
'imamu' written backwards gives 'UMAMI'.
(Other definitions for umami that I've seen before include "Newly discovered taste" , "Savoury flavour" , "Savoury taste sensation produced by glutamates - I, a mum (anag)" , "meaty taste" , "Fifth flavour" .)