She plays a series of jazz chords for law officers (8)

I believe the answer is:

sheriffs

'law officers' is the definition.
(sheriff is a kind of law officer)

'she plays a series of jazz chords' is the wordplay.
'plays a series of jazz chords' becomes 'riffs' (riffing is a style of jazz playing).
'she'+'riffs'='SHERIFFS'

'for' acts as a link.

(Another definition for sheriffs that I've seen is " Police".)

I've seen this clue in The Times.

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