Solid finale with 'Posh' leading group (8)

I believe the answer is:

enduring

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'solid' is the definition.
(thesaurus)

'finale with posh leading group' is the wordplay.
'finale' becomes 'end' (I've seen this before).
'with' is a charade indicator (letters next to each other).
'posh' becomes 'u' (abbreviation for upper-class - opposite to non-u).
'leading group' becomes 'ring' (I am not sure about the 'leading' bit.**).
'end'+'u'+'ring'='ENDURING'

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(Other definitions for enduring that I've seen before include "Lasting' tolerating" , "showing toleration" , "Lasting, unceasing" , "Going through" , "having lasting qualities" .)

I've seen this clue in The Telegraph.

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