Hits a brick wall on both sides of Dublin terrace (4)

I believe the answer is:

hill

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

'terrace' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe there's a link between them I don't understand?

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for hill that I've seen before include "Mount" , "Small mountain" , "Canvasser of opinions" , "Box ---, Emma picnic site (J.Austen)" , "Gradient" .)

I've seen this clue in the Irish Times and the Irish Times (Crosaire).

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