Said to join songwriter Roach to make fiesta music? (8)

I believe the answer is:

mariachi

I'm a little stuck... Click here to teach me more about this clue!

'music?' is the definition.
(I've seen this before)

I can't explain the remainder of the clue.

(Other definitions for mariachi that I've seen before include "Utters" , "one who performs music" , "Mexican street musician" , "Mexican folk music style" , "street musicians?" .)

I've seen this clue in the Sydney Morning Herald.

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