Looked like Greeks regularly exploited space up top (9)
I believe the answer is:
resembled
'looked like' is the definition.
(I've seen this before)
'greeks regularly exploited space up top' is the wordplay.
I cannot really see how this works, but
'space' could be 'em' (in typography, a space as wide as a letter 'm') and 'em' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for resembled that I've seen before include "Favoured" , "Looked like" .)