Complain open clothes showing boob? (9)
I believe the answer is:
oversight
'boob?' is the definition.
(boob can mean a mistake)
'complain open clothes' is the wordplay.
'complain' becomes 'sigh' (you might sigh when complaining).
'open' becomes 'overt' (associated in meaning).
'clothes' means one lot of letters goes inside another (inserted letters are clothed in others).
'sigh' put within 'overt' is 'OVERSIGHT'.
'showing' acts as a link.
(Other definitions for oversight that I've seen before include "Slip-up" , "what supervisor has" , "Failure to notice something" , "Carelessness" , "error" .)