Overlook nothing in Niger disaster (6)
I believe the answer is:
ignore
'overlook' is the definition.
(I've seen this in another clue)
'nothing in niger disaster' is the wordplay.
'nothing' becomes 'O' (O resembles 0).
'in' is an insertion indicator.
'disaster' indicates an anagram.
'niger' anagrammed gives 'ignre'.
'o' inserted into 'ignre' is 'IGNORE'.
(Other definitions for ignore that I've seen before include "Pay no attention to, disregard" , "Pay no heed to" , "Spurn" , "Walk away from" , "Forget" .)