Faces unhappy moderates (5,4)

I believe the answer is:

tones down

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'moderates' is the definition.
('tone down' can be a synonym of 'moderate')

'faces unhappy' is the wordplay.
'faces' becomes 'tones' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'unhappy' becomes 'down' (down can mean sad).
'tones'+'down'='TONES DOWN'

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I've seen this clue in The Times.

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