Question turned up on parliamentarian (4)
I believe the answer is:
pump
'question' is the definition.
(pumping is a kind of questioning)
'turned up on parliamentarian' is the wordplay.
'turned' says the letters should be written backwards.
'up on' becomes 'up' (similar in meaning).
'parliamentarian' becomes 'MP' (Member of Parliament).
'up' written backwards gives 'pu'.
'pu'+'mp'='PUMP'
(Other definitions for pump that I've seen before include "Device to move fluid or gas by pressure or suction" , "Machine for driving air or liquid" , "The heart is one" , "Device for moving liquids by force or suction" , "Device for driving air or liquid" .)