Ill-advised outbreak (4)
I believe the answer is:
rash
This clue is a double definition.
'ill-advised' is the first definition.
(both can mean unwise)
'outbreak' is the second definition.
(rash can mean a sudden outbreak)
(Other definitions for rash that I've seen before include "Hotheaded" , "Incautious" , "Red area on skin" , "sign of irritation?" , "(Armed) incursion (into another country)" .)