Police caught lad misbehaving - a minor fault (10)
I believe the answer is:
peccadillo
'a minor fault' is the definition.
(I've seen this before)
'police caught lad misbehaving' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'misbehaving' indicates anagramming the letters.
'police'+'c'+'lad'='policeclad'
'policeclad' with letters rearranged gives 'PECCADILLO'.
(Other definitions for peccadillo that I've seen before include "Trifling fault - I called cop (anag)" , "minor misdemeanour" , "Minor sin or fault" , "minor faux pas" , "A little wrong" .)