Old mariner's chief support obtained from cinema bar (9)

I believe the answer is:

mainbrace

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'old mariner's chief support obtained' is the definition.
I can't judge whether this defines the answer.

'from cinema bar' is the wordplay.
'from' indicates anagramming the letters (from the letters).
'cinema'+'bar'='cinemabar'
'cinemabar' is an anagram of 'MAINBRACE'.

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(Other definitions for mainbrace that I've seen before include "Part of rigging" , "may get spliced at sea" , "that got spliced" , "rope" , "It's spliced aboard" .)

I've seen this clue in The Globe and Mail.

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