Form of stapler a builder may use (7)

I believe the answer is:

plaster

I'm a little stuck... Click here to teach me more about this clue!

'a builder may use' is the definition.
I can't judge whether this defines the answer.

'form of stapler' is the wordplay.
'form of' is an anagram indicator (the letters need to be in another 'form').
'stapler' anagrammed gives 'PLASTER'.

Can you help me to learn more?

(Other definitions for plaster that I've seen before include "cake" , "Adhesive dressing" , "Wall finish - protection for cut" , "Smooth covering for walls and ceilings" , "Stucco" .)

I've seen this clue in the Evening Standard.

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