Eccentric Conservative standing (5)
I believe the answer is:
crank
'eccentric' is the definition.
(I know that crank is a type of eccentric)
'conservative standing' is the wordplay.
'conservative' becomes 'C' (UK political abbreviation).
'standing' becomes 'rank' (I've seen this in another clue).
'c'+'rank'='CRANK'
(Other definitions for crank that I've seen before include "Person of eccentric habits" , "Person with strange ideas, or machine part" , "Turn a handle - weirdo" , "Turn (engine handle); eccentric" , "Wind (up) - oddball" .)