Musical ornament mentor modified to conceal diamonds (7)

I believe the answer is:

mordent

'musical ornament' is the definition.
(I've seen this before)

'mentor modified to conceal diamonds' is the wordplay.
'modified' is an anagram indicator.
'to conceal' is an insertion indicator.
'diamonds' becomes 'd' (abbreviation in bridge say).
'mentor' anagrammed gives 'morent'.
'morent' enclosing 'd' is 'MORDENT'.

(Another definition for mordent that I've seen is " Musical ornament involving rapid alternation of adjacent notes".)

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