Last car in America has shorter boot in case (7)

I believe the answer is:

caboose

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'last car' is the definition.
(I've seen this in another clue)

'shorter boot in case' is the wordplay.
'shorter' means to remove the last letter.
'in' is an insertion indicator.
'boot' with its last letter removed is 'boo'.
'boo' inserted within 'case' is 'CABOOSE'.

'in america has' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.

Can you help me to learn more?

(Other definitions for caboose that I've seen before include "Kitchen on ship's deck" , "American at the rear" , "US train crew's accommodation" .)

I've seen this clue in The Independent.

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