Hit by runaway trucks (6)
I believe the answer is:
struck
'hit' is the definition.
(I've seen this before)
'runaway trucks' is the wordplay.
'runaway' indicates an anagram.
'trucks' is an anagram of 'STRUCK'.
'by' is the link.
(Other definitions for struck that I've seen before include "Took industrial action" , "set out" , "Thumped" , "Walloped" , "'Hit, slapped (6)'" .)