Prevent Middle Eastern state first (5)
I believe the answer is:
avert
'prevent' is the definition.
(averting is a kind of preventing)
'middle eastern state first' is the wordplay.
'middle' indicates the central letters.
'state' becomes 'aver' (I've seen this before**).
'first' is a charade indicator (letters next to each other).
The middle letter of 'eastern' is 't'.
't' after 'aver' is 'AVERT'.
(Other definitions for avert that I've seen before include "Stave off" , "Head off" , "Prevent, ward off" , "Turn aside or ward off" , "Prevent from occurring" .)