Crossword Genius

ROME GAVE barrier from top to bottom? (5,8,5)


I believe the answer is:

great dividing range

I'm a little stuck... Click here to teach me more about this clue!

'rome gave barrier' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'from top to bottom?' is the wordplay.
I cannot really see how this works, but
'from' could be 'in' (I've seen this in other clues) and 'in' is found in the answer.
'top' could be 'great' (both can mean excellent) and 'great' is found within the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.
Want a hint initially instead of a full solution? Install my app