One who may mock pollsters during half of electioneering (8)
I believe the answer is:
humorist
'one who may mock' is the definition.
(someone making humour of a situation)
'pollsters during half of electioneering' is the wordplay.
'pollsters' becomes 'mori' (market research company Ipsos MORI).
'during' indicates putting letters inside.
'half of' means to take half the letters.
'electioneering' becomes 'hustings' (I've seen this before).
'hustings' with half the letters taken is 'hust'.
'mori' going into 'hust' is 'HUMORIST'.
(Other definitions for humorist that I've seen before include "A comedian" , "Comic story writer" , "Perhaps Thurber" , "Card" .)