Careless mistake with wearing shoes (8)
I believe the answer is:
slipshod
'careless' is the definition.
('slipshod' can be similar in meaning to 'careless')
'mistake with wearing shoes' is the wordplay.
'mistake' becomes 'slip' (slip is a kind of mistake).
'with' is a charade indicator (letters next to each other).
'wearing shoes' becomes 'shod' (I've seen this before).
'slip'+'shod'='SLIPSHOD'
(Other definitions for slipshod that I've seen before include "Inattentive" , "Careless, slovenly" , "Disorganised" , "Sloppy and haphazard" , "Carelessly done" .)