Juliet isn't there to nudge Romeo: he's a stable chap (6)
I believe the answer is:
ostler
This clue could be a double definition.
'juliet isn't there to nudge romeo he's' is the first definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'a stable chap' is the second definition.
The definition and answer can be both people as well as being singular nouns.
Maybe they are linked in a way I don't understand?
Can you help me to learn more?
(Other definitions for ostler that I've seen before include "Horse minder" , "Inn servant" , "Stableman at old coaching inn" , "Inn's stableman, of old" , "Inn's carer for horses" .)