Beer’s healthy if the head is removed (3)

I believe the answer is:

ale

'beer's' is the definition.
(I've seen this before)

I don't understand how the remainder of the clue works.

(Other definitions for ale that I've seen before include "festival" , "Grog" , "Light-coloured beer" , "Beer consumed in sales" , "Alcohol" .)

I've seen this clue in The Times.

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