Crossword Genius

What we must play off and on to a balding captain? (8)

Ross

I believe the answer is:

obligati

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'what we must play' is the definition.
I can't judge whether this definition defines the answer.

'off and on to a balding captain?' is the wordplay.
'off and on' indicates alternate letters (letters used at regular intervals).
'to'+'a'+'balding'+'captain'='toabaldingcaptain'
The alternating letters of 'toabaldingcaptain' are 'OBLIGATI'.

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I've seen this clue in The Telegraph.
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