Crossword Genius

Being successful, UN had pop tune composed (2,3,2-3-2)

Ross

I believe the answer is:

on the up-and-up

'being successful' is the definition.
(thesaurus)

'un had pop tune composed' is the wordplay.
'composed' is an anagram indicator.
'un'+'had'+'pop'+'tune'='unhadpoptune'
'unhadpoptune' with letters rearranged gives 'ON THE UP AND UP'.

I've seen this clue in The Everyman puzzle in The Observer.
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