Someone terrible following game around in vehicle (7)
I believe the answer is:
minivan
'vehicle' is the definition.
(I've seen this before)
'someone terrible following game around' is the wordplay.
'someone terrible' becomes 'ivan' (Russian tsar Ivan the Terrible).
'following' means one lot of letters go next to another.
'game' becomes 'nim' (I've seen this before).
'around' is a reversal indicator.
'nim' backwards is 'min'.
'ivan' after 'min' is 'MINIVAN'.
'in' acts as a link.
(Other definitions for minivan that I've seen before include "transporter" , "Transport" , "vehicle" .)