Material Chekhov initially included in his play rewritten (8)
I believe the answer is:
physical
'material' is the definition.
('physical' can be similar in meaning to 'material')
'chekhov initially included in his play rewritten' is the wordplay.
'initially' says to take the initial letters.
'included in' is an insertion indicator.
'rewritten' indicates an anagram.
The first letter of 'chekhov' is 'c'.
'his'+'play'='hisplay'
'hisplay' anagrammed gives 'physial'.
'c' going inside 'physial' is 'PHYSICAL'.
(Other definitions for physical that I've seen before include "Having a material existence" , "Exam" , "Check-up" , "Medical check" , "Relating to the body, not the mind" .)