Outline of first dictionary by English writer (8)
I believe the answer is:
Here is my best explanation:
'outline' is the definition.
('describe' can be a synonym of 'outline')
'first dictionary by english writer' is the subsidiary indication.
'first' says to take the initial letters.
'by' says to put letters next to each other.
'english' becomes 'e' (abbreviation).
'writer' becomes 'scribe' (scribe is a kind of writer**).
The initial letter of 'dictionary' is 'd'.
'of' is the link.
(Other definitions for describe that I've seen before include "Tell what something is like", "Give an account of in words", "Say what something is like (8)", "Report in detail", "Draw (figure); give account of", "Portray in words", "Draw (a geometrical figure)", "Represent in words", "Illustrate" and "Depict".)