Tea service set up after start of afternoon (5)
I believe the answer is:
assam
'tea' is the definition.
(I've seen this before)
'service set up after start of afternoon' is the wordplay.
'service' becomes 'mass' (I've seen this in other clues**).
'set up' says the letters should be written in reverse.
'after' says to put letters next to each other.
'start of' says to take the initial letters.
The first letter of 'afternoon' is 'a'.
'mass' back-to-front is 'ssam'.
'ssam' after 'a' is 'ASSAM'.
(Other definitions for assam that I've seen before include "India tea-producing state" , "place associated with tea" , "Indian tea region" , "State of NE India" , "Tea state of India" .)