Like columns to be representative, not conservative (5)
I believe the answer is:
ionic
'like columns' is the definition.
(ionic is a type of Greek column)
'representative not conservative' is the wordplay.
'representative' becomes 'iconic'.
'not' indicates named letters should be taken away.
'conservative' becomes 'c' (abbreviation commonly used in UK politics).
'iconic' with 'c' taken out is 'IONIC'.
'to be' acts as a link.
(Other definitions for ionic that I've seen before include "Style of Greek architecture" , "Support (a weight)" , "in ancient Greece?" , "classical Greek design" , "Greek order" .)