Lettering guide (7)
I believe the answer is:
stencil
'lettering guide' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for stencil that I've seen before include "Design inked through perforated sheet" , "Copy" , "Perforated sheet for producing patterns or symbols" , "means of decoration" , "Cut out pattern for painting a design" .)