Tea that's inferior to instant coffee (5)
I believe the answer is:
mocha
'coffee' is the definition.
(I know that mocha is a type of coffee)
'tea that's inferior to instant' is the wordplay.
'tea' becomes 'cha' (cha is a type of tea).
'that's inferior to' says to put letters next to each other (in a down clue, some letters go below others).
'instant' becomes 'mo'.
'cha' after 'mo' is 'MOCHA'.
(Other definitions for mocha that I've seen before include "It may end up as grounds" , "Deep brown; a fine coffee" , "Strong dark coffee" , "Dark brown" , "Arabian coffee" .)