Elevated religious leader with upper-class taste (5)
I believe the answer is:
umami
'taste' is the definition.
(I know that umami is a type of taste)
'elevated religious leader with upper-class' is the wordplay.
'elevated' shows that the letters should be reversed in order (in a down clue, letters go up).
'religious leader' becomes 'imam' (I've seen this before).
'with' means one lot of letters go next to another.
'upper-class' becomes 'u' (similar in meaning).
'imam' in reverse letter order is 'mami'.
'mami' put after 'u' is 'UMAMI'.
(Other definitions for umami that I've seen before include "Savoury taste sensation produced by glutamates - I, a mum (anag)" , "acquired taste perhaps" , "Fifth flavour" , "Savoury flavour" , "meaty taste" .)