Hundreds of square metres (4)
I believe the answer is:
ares
'hundreds' is the definition.
The definition and answer can be both quantities as well as being plural nouns.
Maybe there's a link between them I don't understand?
'square metres' is the wordplay.
I cannot quite understand how this works, but
'square' could be 's' (abbreviation) and 's' is found within the answer.
The remaining letters 'are' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'of' acts as a link.
Can you help me to learn more?
(Other definitions for ares that I've seen before include "figure of worship" , "Land measures" , "Greek god of war" , "Belligerent god" , "Olympian" .)