Sold grass containing dock (8)

I believe the answer is:

retailed

'sold' is the definition.
(retailing is a kind of selling)

'grass containing dock' is the wordplay.
'grass' becomes 'reed' (I've seen this before).
'containing' is an insertion indicator.
'dock' becomes 'tail' ('tail' can be a synonym of 'dock').
'reed' going around 'tail' is 'RETAILED'.

(Another definition for retailed that I've seen is " Sold".)

I've seen this clue in The Telegraph.

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