Leave one of the later courses, by the sound of it (6)

I believe the answer is:

desert

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'leave' is the definition.
(desert can mean to leave or abandon)

I don't understand the remainder of the clue.

(Other definitions for desert that I've seen before include "See 1" , "Waterless area of land" , "Defect, forsake" , "See 23" , "Sahara, Gobi, etc" .)

I've seen this clue in The Irish Independent.

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