Jolts a parliamentarian in a bus (5)
I believe the answer is:
bumps
'jolts' is the definition.
(I've seen this before)
'a parliamentarian in a bus' is the wordplay.
'a parliamentarian' becomes 'MP' (Member of Parliament).
'in' means one lot of letters goes inside another.
'mp' placed into 'bus' is 'BUMPS'.
(Other definitions for bumps that I've seen before include "Hits" , "Knocks (given on one's birthday?)" , "Small protuberances; knocks lightly into" , "sleeping policemen?" , "Bulges" .)