The pies I test out on father (7)

I believe the answer is:

patties

'the pies' is the definition.
(patty is a kind of pie)

'i test out on father' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'on' indicates putting letters inside (as in clothing 'on' a person).
'father' becomes 'pa' (pa can mean dad or father).
'i'+'test'='itest'
'itest' with letters rearranged gives 'tties'.
'tties' enclosing 'pa' is 'PATTIES'.

I've seen this clue in the Evening Standard.

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