Edgar gutted by cryptic containing nothing designed to be easy (9)
I believe the answer is:
ergonomic
'designed to be easy' is the definition.
(designed for ease or comfort)
'edgar gutted by cryptic containing nothing' is the wordplay.
'gutted' means to remove the middle letters (to gut something is to remove its insides).
'by' says to put letters next to each other.
'cryptic' becomes 'gnomic' (gnomic can mean cryptic or enigmatic).
'containing' is an insertion indicator.
'nothing' becomes 'O' (O resembles 0).
'edgar' with its centre taken out is 'er'.
'gnomic' enclosing 'o' is 'gonomic'.
'er'+'gonomic'='ERGONOMIC'
(Other definitions for ergonomic that I've seen before include "Designed for efficiency and comfort in the working environment" , "operating with maximum efficiency" , "using biotechnology" , "Studying man in his work environment" , "Designed for work efficiency" .)