Expensive case of lemonade drinks for jumpers (14)

I believe the answer is:

steeplechasers

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'jumpers' is the definition.
Although both the answer and definition are plural nouns, I can't see how they can define each other.

'expensive case of lemonade drinks' is the wordplay.
'expensive' becomes 'steep' (I've seen this before).
'case of' suggests removing the centre (outsides of).
'drinks' becomes 'chasers' (I have seen 'further drinks' mean 'chasers' so perhaps 'drinks' could also mean 'chasers').
'lemonade' with its centre taken out is 'le'.
'steep'+'le'+'chasers'='STEEPLECHASERS'

'for' is the link.

Can you help me to learn more?

I've seen this clue in The Telegraph.

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