Sign females, ignoring leader (4)
I believe the answer is:
omen
'sign' is the definition.
(omen is a kind of sign)
'females ignoring leader' is the wordplay.
'females' becomes 'women' (woman is a kind of female).
'ignoring leader' means to remove the first letter.
'women' with its initial letter taken away is 'OMEN'.
(Other definitions for omen that I've seen before include "Warning - sign" , "Harbinger, portent" , "Portent, prophetic sign" , "Auspice" , "Augury, portent" .)