An import brought back from Ragusa? (5)

I believe the answer is:

sugar

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

'an import' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.

'brought back from ragusa?' is the wordplay.
'SUGAR' is hidden backwards within the letters.
But, I'm not sure how this is indicated.

Can you help me to learn more?

(Other definitions for sugar that I've seen before include "--- Ray Robinson, boxer" , "Common sweetener" , "Sucrose" , "Cane or beet product" , "Sweet white substance" .)

I've seen this clue in the Evening Standard.

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