Setter repeats Indian music ascending (4-4)
I believe the answer is:
agar-agar
'setter' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'repeats indian music ascending' is the wordplay.
'repeats' says to double the letters.
'indian music' becomes 'raga' (I've seen this before).
'ascending' says the letters should be written in reverse.
'raga' back-to-front is 'agar'.
'agar' doubled is 'AGAR-AGAR'.
Can you help me to learn more?
(Other definitions for agar-agar that I've seen before include "Jelly from seaweed" , "Food thickener from seaweed" , "Thickener obtained from seaweed" , "Gelatinous thickening for food" .)