Overwhelm a small Scots settlement with 500 (7)

I believe the answer is:

astound

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'overwhelm' is the definition.
(thesaurus)

'a small scots settlement with 500' is the wordplay.
'small scots settlement' becomes 'stoun' (I can't explain this - if you can you should believe this answer much more).
'with' means one lot of letters go next to another.
'n00' becomes 'D' (Roman numeral for n00).
'a'+'stoun'+'d'='ASTOUND'

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(Other definitions for astound that I've seen before include "floor" , "Bewilder" , "Amaze, astonish" , "Stupefy" , "Stagger" .)

I've seen this clue in The Times.

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