Certainly not! (2,3,4)
'certainly not' is the definition.
(phrase used to express a denial or refusal)
This is the entire clue.
(Other definitions for no fear that I've seen before include "Never" , "Absolutely not" , "Definitely not (sl.)" , "Not on your life, certainly not" , "Very clear Five ac [REFUSAL]" .)
(Another definition for no way jose that I've seen is " Absolutely not".)