Greek character's climbing entire central Doric column (6)
I believe the answer is:
pillar
'column' is the definition.
(synonyms)
'greek character's climbing entire central doric' is the wordplay.
'greek character' becomes 'pi' (letter from the Greek alphabet).
'climbing' shows that the letters should be reversed in order (in a down clue, letters climb up).
'entire' becomes 'all' (I've seen this in other clues).
'central' indicates the central letters.
The middle of 'doric' is 'r'.
'all' written backwards gives 'lla'.
'pi'+'lla'+'r'='PILLAR'
(Other definitions for pillar that I've seen before include "Column; admired member (of community)" , "Support structure" , "Vertical stone support" , "Architectural support" , "Upright post" .)