Crossword Genius

Great asset in Colombo once (4)

Ross

I believe the answer is:

boon

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'great asset' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

'in colombo once' is the wordplay.
'in' indicates a hidden word.
'BOON' can be found hidden inside 'colombo once'.

Can you help me to learn more?

(Other definitions for boon that I've seen before include "Godsend" , "Blessing - sort of companion?" , "Something beneficial - a blessing" , "Favour, request" , "Beneficial thing" .)

I've seen this clue in The Sun.
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