Vehicles needed if craft disintegrates (7)
I believe the answer is:
traffic
'vehicles' is the definition.
(I've seen this before)
'if craft disintegrates' is the wordplay.
'disintegrates' indicates an anagram (I've seen 'disintegrated' mean this).
'if'+'craft'='ifcraft'
'ifcraft' anagrammed gives 'TRAFFIC'.
'needed' is the link.
(Other definitions for traffic that I've seen before include "Flow of vehicles" , "Vehicles coming and going" , "Communications" , "Vehicle flow" , "Illegally push" .)