Hit by small lorry (6)
I believe the answer is:
struck
'hit' is the definition.
(strike can mean to hit)
'by small lorry' is the wordplay.
'by' says to put letters next to each other.
'small' becomes 's' (abbreviation - e.g. clothes size).
'lorry' becomes 'truck' (I've seen this before).
's' put next to 'truck' is 'STRUCK'.
(Other definitions for struck that I've seen before include "Walloped" , "Hit - withheld labour" , "Punched" , "Given blows - affected instantaneously" , "hit hard" .)