Keep flat after pal unexpectedly leaves university (7)

I believe the answer is:

plateau

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'keep flat' is the definition.
'plateau' can be an answer for 'flat' (thesaurus). I'm unsure of the 'keep' bit.

'pal unexpectedly leaves university' is the wordplay.
'unexpectedly' indicates an anagram.
'leaves' becomes 'tea' (as in tea leaves).
'university' becomes 'U' (abbreviation for university).
'pal' anagrammed gives 'pla'.
'pla'+'tea'+'u'='PLATEAU'

'after' acts as a link.

Can you help me to learn more?

(Other definitions for plateau that I've seen before include "plane" , "State of little change after a period of activity" , "Area of level high ground" , "Large level tract of elevated land" , "High tableland" .)

I've seen this clue in The Times.

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