Customers of SPAR not fickle (7)

I believe the answer is:

patrons

'customers' is the definition.
(I know this)

'spar not fickle' is the wordplay.
'fickle' indicates an anagram.
'spar'+'not'='sparnot'
'sparnot' is an anagram of 'PATRONS'.

'of' is the link.

I've seen this clue in The Telegraph.

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