Ruin of the French city sacked by Greeks (7)

I believe the answer is:

destroy

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'ruin' is the definition.
(I know that ruin can be written as destroy)

'of the french city sacked by greeks' is the wordplay.
'of the french' becomes 'dela' ('of the' in French).
'city' becomes 'LA' (Los Angeles).
'sacked' is a deletion indicator.
'by greeks' becomes 'stroy' (I can't explain this - if you can you should believe this answer much more).
'dela' with 'la' taken out is 'de'.
'de'+'stroy'='DESTROY'

Can you help me to learn more?

(Other definitions for destroy that I've seen before include "Ruin or defeat roundly" , "Wreck" , "Demolish; pull down" , "Annihilate" , "Ruin, put an end to" .)

I've seen this clue in The Guardian.

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