Eliot’s first play about small island (4)
I believe the answer is:
eyot
'small island' is the definition.
(I've seen this before)
'eliot's first play about' is the wordplay.
'first' suggests taking the first letters.
'play' becomes 'toy' ('toy' can be a synonym of 'play').
'about' is a reversal indicator.
The first letter of 'eliot' is 'e'.
'toy' written backwards gives 'yot'.
'e'+'yot'='EYOT'
(Other definitions for eyot that I've seen before include "Fawlty Towers waiter" , "There's one at Chiswick" , "Little island in a river or lake" , "isle" , "Small river island" .)