Vast rain spreads in different forms (8)

I believe the answer is:

variants

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'different forms' is the definition.
'variants' can be an answer for 'forms' ('variant' can be a synonym of 'form'). I am not certain of the 'different' bit.

'vast rain spreads' is the wordplay.
'spreads' is an anagram indicator (I've seen 'spreading of' mean this).
'vast'+'rain'='vastrain'
'vastrain' with letters rearranged gives 'VARIANTS'.

'in' is the link.

Can you help me to learn more?

(Other definitions for variants that I've seen before include "They're not the same" , "Non-standard types" .)

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

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