Illustrations in Darwin drawn by head of grammar school (8)
I believe the answer is:
drawings
'illustrations' is the definition.
(I've seen this before)
'darwin drawn by head of grammar school' is the wordplay.
'drawn' indicates anagramming the letters (the letters drawn up in a different way).
'by' says to put letters next to each other.
'head of' says to take the initial letters.
'school' becomes 's' ().
The initial letter of 'grammar' is 'g'.
'darwin' is an anagram of 'drawin'.
'drawin'+'g'+'s'='DRAWINGS'
'in' is the link.
(Other definitions for drawings that I've seen before include "Illustrations, draft plans" , "Cleaned with water" , "Illustrations by hand" , "Sketches or draughts" .)