Reforming MP, Liberal, I’m second in election (8)
I believe the answer is:
plimsoll
'reforming mp' is the definition.
(Samuel Plimsoll, MP known for social reforms)
'liberal i'm second in election' is the wordplay.
'liberal' becomes 'l' (abbreviation).
'second' becomes 's' (common abbreviation).
'in' is an insertion indicator.
'election' becomes 'poll' (I've seen this before).
'l'+'im'+'s'='lims'
'lims' going into 'poll' is 'PLIMSOLL'.
(Other definitions for plimsoll that I've seen before include "Canvas shoe" , "Mark on ship's side to indicate limit of loading" , "-- Line, a mark on ships showing loading" , "Light gym shoe and waterline" , "This line on ship's side measures degree of loading" .)