Forestall (5)
'forestall' is the definition.
(I know that forestall can be written as pre-empt)
This is all the clue.
(Other definitions for pre-empt that I've seen before include "Grab first; forestall" , "Acquire before others can do so" , "Render useless by prior action" , "Secure as first-comer" , "Forestall, do before anyone else can" .)
'forestall' is the definition.
(averting is a kind of forestalling)
This is all the clue.
(Other definitions for avert that I've seen before include "Head off" , "Parry" , "use preventive measures" , "Turn away, prevent" , "Ward off, deflect" .)