Romeo and Juliet, both principally drunk bottle (8)
I believe the answer is:
jeroboam
'bottle' is the definition.
(I know that jeroboam is a type of wine bottle)
'romeo and juliet both principally drunk' is the wordplay.
'principally' indicates taking the first letters.
'drunk' indicates an anagram.
The initial letters of 'and juliet both' is 'ajb'.
'romeo'+'ajb'='romeoajb'
'romeoajb' with letters rearranged gives 'JEROBOAM'.
(Other definitions for jeroboam that I've seen before include "a lot of bottle?" , "Very large wine bottle named after old king of Israel" , "'Large wine bottle, equal to four standard ones (8)'" , "Wine bottle 4-12 times the ordinary size" , "Four-times bottle size" .)