A layout as required by a piece of material (6)
I believe the answer is:
format
'a layout' is the definition.
(I've seen this before)
'required by a piece of material' is the wordplay.
I cannot quite see how this works, but
'by' could be 'at' and 'at' is present in the answer.
'piece' could be 'r' (abbreviation for Rook) and 'r' is present in the answer.
'of' could be 'o' and 'o' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'as' acts as a link.
Can you help me to learn more?
(Other definitions for format that I've seen before include "Shape and style as of book" , "Way in which something is presented" , "Structure, layout" , "The shape and size, of a book say" , "magazine" .)