Its sheer drudgery for university teacher to take essential book (10)

I believe the answer is:

donkeywork

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'its sheer drudgery for university' is the definition.
I can't tell whether this definition defines the answer.

'teacher to take essential book' is the wordplay.
'teacher' becomes 'don' (don is a kind of teacher).
'to take' means one lot of letters go next to another.
'essential' becomes 'key' (key can mean essential or important).
'book' becomes 'work' (I can't justify this - if you can you should believe this answer much more).
'don'+'key'+'work'='DONKEYWORK'

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I've seen this clue in The Irish News.

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