Busy bee ignored hazard (4)
I believe the answer is:
risk
'hazard' is the definition.
(synonyms)
'busy bee ignored' is the wordplay.
'busy' becomes 'brisk' (brisk can mean fast or busy).
'bee' becomes 'b'.
'ignored' suggests deleting specific letters.
'brisk' with 'b' removed is 'RISK'.
(Other definitions for risk that I've seen before include "Gamble" , "Endanger, jeopardise" , "dangerous thing" , "Assessment of potential dangers -- any silk saris (anag)" , "Take a chance" .)