Axes by stone portico in Greece (4)
I believe the answer is:
xyst
'portico in greece' is the definition.
The definition suggests a singular noun which matches the answer.
'axes by stone' is the wordplay.
'axes' becomes 'xy' (x axis and y axis).
'by' is a charade indicator (letters next to each other).
'stone' becomes 'st'.
'xy'+'st'='XYST'
Can you help me to learn more?
(Other definitions for xyst that I've seen before include "Covered portico" , "Tree-lined walk in Ancient Rome" .)