Uncover a bit of northern Greek architecture (4)
I believe the answer is:
rake
'uncover' is the definition.
(eg a rake may remove a covering of leaves)
'a bit of northern greek architecture' is the wordplay.
'northern' says the letters should be written in reverse (in a down clue, letters go up or 'north').
'a bit of' indicates a hidden word (I've seen 'a bit' mean this (the answer is formed by a bit of the clue)).
'ekar' can be found hidden inside 'greek architecture'.
'ekar' back-to-front is 'RAKE'.
(Other definitions for rake that I've seen before include "Debauched person found in the garden" , "Gardening implement" , "One with teeth" , "One making progress in series of pictures" , "Scraper - womaniser" .)