I’m USA caper, possibly, around cold water? But NZ are the holders! (8,3)

I believe the answer is:

americas cup

I'm a little stuck... Click here to teach me more about this clue!

'nz are the holders' is the definition.
I can't judge whether this definition defines the answer.

'i'm usa caper possibly around cold water?' is the wordplay.
'possibly' is an anagram indicator.
'around' means one lot of letters goes inside another.
'cold water?' becomes 'C' (symbol for the cold tap).
'im'+'usa'+'caper'='imusacaper'
'imusacaper' is an anagram of 'ameriascup'.
'ameriascup' going around 'c' is 'AMERICAS CUP'.

'but' is the link.

Can you help me to learn more?

(Other definitions for americas cup that I've seen before include "Competition for boats" , "Yachting prize" , "main competition" , "International yachting trophy" , "Yacht-racing trophy" .)

I've seen this clue in The Independent.

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