Radiant Rod rocking but slowing down (10)

I believe the answer is:

ritardando

'slowing down' is the definition.
(I've seen this before)

'radiant rod rocking' is the wordplay.
'rocking' indicates an anagram.
'radiant'+'rod'='radiantrod'
'radiantrod' is an anagram of 'RITARDANDO'.

'but' acts as a link.

(Another definition for ritardando that I've seen is " slowing down".)

I've seen this clue in The Independent.

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