Some preventing incident (5)
I believe the answer is:
event
'incident' is the definition.
(I've seen this in another clue)
'some preventing' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'EVENT' can be found hidden inside 'preventing'.
(Other definitions for event that I've seen before include "A thing taking place" , "Function" , "400 metres?" , "match" , "Occurren" .)