Stylish man admitted being awful (7)
I believe the answer is:
chronic
'being awful' is the definition.
(old-fashioned slang for 'poor quality')
'stylish man admitted' is the wordplay.
'stylish' becomes 'chic' (similar in meaning).
'man' becomes 'ron' (short for Ronald).
'admitted' means one lot of letters goes inside another (inserted letters get admitted).
'chic' placed around 'ron' is 'CHRONIC'.
(Other definitions for chronic that I've seen before include "(Of illness) slow developing over a long time" , "Of a very poor quality" , "(Of illness) lengthy; very bad (colloq.)" , "(Of illness) long-lasting" , "Of illness, prolonged or constantly recurring" .)