Nullify United Nations’ direct order, for starters (4)
I believe the answer is:
undo
'nullify' is the definition.
(I've seen this before)
'united nations' direct order for starters' is the wordplay.
'for starters' suggests taking the first letters.
The initial letters of 'united nations direct order' is 'UNDO'.
(Other definitions for undo that I've seen before include "Overturn" , "Ruin or loosen ties" , "Bring to ruin" , "Open buttons or ruin" , "Open, a knot say" .)