Throw up, with layabout appearing topless (3)

I believe the answer is:

lob

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'throw up' is the definition.
(I've seen this before)

I can't explain the remainder of the clue.

(Other definitions for lob that I've seen before include "Throw ball in high arc" , "High throw or hit" , "Shot of Murray" , "Fling" , "high return" .)

I've seen this clue in The Times.

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