Rain protector by enclosing some spin (6)

I believe the answer is:

brolly

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'rain protector' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.

'by enclosing some spin' is the wordplay.
'enclosing' is an insertion indicator.
'some spin' becomes 'roll'.
'by' placed around 'roll' is 'BROLLY'.

Can you help me to learn more?

(Other definitions for brolly that I've seen before include "Umbrella (informal)" , "What goes up when rain comes down?" , "Portable rain-shield (abbr.)" , "Cover for head" , "Gamp" .)

I've seen this clue in the Sydney Morning Herald.

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