Outline device to have a lasting impression? (7)

I believe the answer is:

stencil

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'outline device' is the definition.

I don't understand the rest of the clue.

(Other definitions for stencil that I've seen before include "decoration? One must be cut out for it" , "Template for pattern" , "office plate" , "Aid for drawing" , "Method of decorating" .)

I've seen this clue in The Telegraph.

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