Preventing rant, give alternative (8)
I believe the answer is:
averting
'preventing' is the definition.
(averting is a kind of preventing)
'rant give alternative' is the wordplay.
'alternative' indicates an anagram (an alternative ordering of the letters).
'rant'+'give'='rantgive'
'rantgive' anagrammed gives 'AVERTING'.
(Other definitions for averting that I've seen before include "'Heading off, deflecting (8)'" , "Turning aside one's eyes" , "Turning aside and preventing." , "Avoiding" , "Warding off" .)