Macabre morgues upset English (8)
I believe the answer is:
gruesome
'macabre' is the definition.
(I've seen this before)
'morgues upset english' is the wordplay.
'upset' indicates an anagram.
'english' becomes 'e' (abbreviation).
'morgues' anagrammed gives 'gruesom'.
'gruesom'+'e'='GRUESOME'
(Other definitions for gruesome that I've seen before include "terrible" , "Horrifying and revolting" , "Go, resume being revolting or gruesome" , "Revolting, filling one with horror and disgust" , "Extremely unpleasant" .)