Concluded popular female made a mistake (8)
I believe the answer is:
inferred
'concluded' is the definition.
(inferring is a kind of concluding)
'popular female made a mistake' is the wordplay.
'popular' becomes 'in'.
'female' becomes 'f' (abbreviation).
'made a mistake' becomes 'erred' ('err' can be a synonym of 'make a mistake').
'in'+'f'+'erred'='INFERRED'
(Other definitions for inferred that I've seen before include "'Concluded, judged from the facts (8)'" , "Deduced by reasoning" , "Conjectured" , "Rein Fred in because he deduced" .)