Nick may be official in parliament (4)
I believe the answer is:
whip
'official in parliament' is the definition.
(whips enforce party discipline in parliament)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for whip that I've seen before include "Address insultingly" , "The one who enforces discipline in a political party" , "Flog - pinch" , "Legislator appointed by a party to enforce discipline" , "MP enforcing discipline" .)