Joiner employed in building work (6)

I believe the answer is:

cement

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

I don't understand the remainder of the clue.

(Other definitions for cement that I've seen before include "It hardens when mixed with water" , "Mortar; strengthen" , "Ingredient of concrete" , "Bond firmly" , "Building material to bind things" .)

I've seen this clue in The Sun.

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