Very bad part — character in Romeo and Juliet (6)
I believe the answer is:
severe
'very bad' is the definition.
(I've seen this in another clue)
'part character in romeo and juliet' is the wordplay.
'part' becomes 'sever' (severing is a kind of parting).
'character in' means to look at the middle letters (I've seen 'characters in' mean this).
'romeo and juliet' becomes 'shakespeareplay' (I've seen this in another clue).
The middle of 'shakespeareplay' is 'e'.
'sever'+'e'='SEVERE'
(Other definitions for severe that I've seen before include "Forbidding in action or appearance" , "Harsh and unbending" , "Extremely difficult to endure" , "sober" , "Critical" .)