Reversion to type puts Mavis at variance (7)

I believe the answer is:

atavism

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

'mavis at variance' is the wordplay.
'variance' is an anagram indicator.
'mavis'+'at'='mavisat'
'mavisat' is an anagram of 'ATAVISM'.

'to type puts' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.

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(Other definitions for atavism that I've seen before include "Reversion to a former type" , "doing things the old way" , "reverting to type" , "Reversion to primitive type" , "Reversion to the primitive - I am vast (anag)" .)

I've seen this clue in The Globe and Mail.

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