However, large book covering business is expected? (3,2,4)

I believe the answer is:

yet to come

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'expected?' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'however large book covering business' is the wordplay.
'however' becomes 'yet' (I've seen this before).
'large book' becomes 'tome' (a tome is a large or heavy book).
'covering' indicates putting letters inside.
'business' becomes 'co' (short for company).
'tome' going around 'co' is 'tocome'.
'yet'+'tocome'='YET TO COME'

'is' acts as a link.

Can you help me to learn more?

(Another definition for yet to come that I've seen is " Last visitor in 5 [A CHRISTMAS CAROL]".)

I've seen this clue in The Guardian.

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