Very bad style worn by Ron (7)
I believe the answer is:
chronic
'very bad' is the definition.
(I've seen this in other clues)
'style worn by ron' is the wordplay.
'style' becomes 'chic' (chic can mean elegance or style).
'worn by' is an insertion indicator (outside letters are worn by those on the inside).
'chic' placed around 'ron' is 'CHRONIC'.
(Other definitions for chronic that I've seen before include "Awful" , "(Of illness) slow developing over a long time" , "(Of illness) lengthy; very bad (colloq.)" , "(Of disease) long-lasting" , "Of illness, prolonged or constantly recurring" .)