Layout of backroom, a kind of square (6)
I believe the answer is:
format
'layout' is the definition.
(I've seen this before)
'backroom a kind of square' is the wordplay.
I cannot quite understand how this works, but
'a' is present in the answer.
'kind' could be 'form' (synonyms) and 'form' is present in the answer.
'square' could be 't' (a T-Square is a technical drawing instrument) and 't' is present in the answer.
No letters remain.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for format that I've seen before include "magazine" , "General arrangement of a publication" , "Broadsheet or tabloid, say" , "Arrangement or lay-out, say of book" , "Size, style and shape, of books say" .)