Muscle was wasted with author finding substantial growth (6,9)

I believe the answer is:

walrus moustache

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'substantial growth' is the definition.
The definition suggests a singular noun which matches the answer.

'muscle was wasted with author' is the wordplay.
'wasted with' indicates anagramming the letters.
'muscle'+'was'='musclewas'
'musclewas' with its letters mixed up with 'author' can make 'WALRUS MOUSTACHE'.

'finding' acts as a link.

Can you help me to learn more?

(Other definitions for walrus moustache that I've seen before include "Hairy thing" , "hair" .)

I've seen this clue in The Independent.

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