Very unpleasant morgues upset English (8)
I believe the answer is:
gruesome
'very unpleasant' is the definition.
(I've seen this before)
'morgues upset english' is the wordplay.
'upset' is an anagram indicator.
'english' becomes 'e' (abbreviation).
'morgues' anagrammed gives 'gruesom'.
'gruesom'+'e'='GRUESOME'
(Other definitions for gruesome that I've seen before include "Extremely unpleasant" , "Sickening, macabre" , "Horrifying and revolting" , "Causing horror or repulsion" , "Go, resume being revolting or gruesome" .)