Instructs Eliot to get boxes (3-6)

I believe the answer is:

tea-chests

'boxes' is the definition.
(tea chest is a kind of box)

'instructs eliot' is the wordplay.
'instructs' becomes 'teaches' ('teach' can be a synonym of 'instruct').
'eliot' becomes 'ts' (poet TS Eliot).
'teaches'+'ts'='TEA-CHESTS'

'to get' acts as a link.

I've seen this clue in The Guardian.

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