Light work made of one manager in unresponsive state (5,5)
I believe the answer is:
comic opera
'light work' is the definition.
(type of light or trivial work)
'one manager in unresponsive state' is the wordplay.
'one' becomes 'I' (Roman numeral).
'manager' becomes 'coper' (someone who manages or copes).
'in' means one lot of letters goes inside another.
'unresponsive state' becomes 'coma' (a coma is an unconscious state).
'i'+'coper'='icoper'
'icoper' put into 'coma' is 'COMIC OPERA'.
'made of' is the link.
(Other definitions for comic opera that I've seen before include "It has dialogue as well as singing" , "Milton perhaps" , "Something by Offenbach" , "Amusing stage work" , "many will laugh at that" .)