Definitely not! (2,4)

I think it could be either:

Which length description are you looking for?:

2,3

2,4

no fear

'definitely not' is the definition.
(I've seen this before)

This is all the clue.

(Other definitions for no fear that I've seen before include "Never" , "Very clear Five ac [REFUSAL]" , "Certainly not (informal)" , "Definitely not (informal)" , "What 7 [INTREPID] person will have" .)

I've seen this clue in The Independent and The Guardian.

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