Prosaic English studio edited (7)
I believe the answer is:
tedious
'prosaic' is the definition.
(thesaurus)
'english studio edited' is the wordplay.
'english' becomes 'E' (abbreviation).
'edited' is an anagram indicator.
'e'+'studio'='estudio'
'estudio' with letters rearranged gives 'TEDIOUS'.
(Other definitions for tedious that I've seen before include "awfully boring" , "Boring, monotonous" , "Dull as ditchwater" , "drab" , "Long, slow, dull" .)