After some deliveries, article is on shelf for unrestricted purchase (4-3-7)

I believe the answer is:

over-the-counter

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'unrestricted purchase' is the definition.
The definition suggests a singular noun which matches the answer.

'after some deliveries article is on shelf' is the wordplay.
'after' means one lot of letters go next to another.
'some deliveries' becomes 'over' (a cricket over consists of six deliveries).
'article' becomes 'the' (the definite article in English).
'is on shelf' becomes 'counter' (I can't explain this - if you can you should believe this answer much more).
'over'+'the' is 'overthe'.
'overthe'+'counter'='OVER-THE-COUNTER'

'for' acts as a link.

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I've seen this clue in The Times.

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