Romeo joins musical theatre company in US city (4)
I believe the answer is:
reno
'us city' is the definition.
(city in Nevada)
'romeo joins musical theatre company' is the wordplay.
'romeo' becomes 'r' (phonetic alphabet: alpha, bravo, charlie etc.).
'joins' means one lot of letters go next to another.
'musical theatre company' becomes 'eno' (I can't justify this - if you can you should give a lot more credence to this answer).
'r'+'eno'='RENO'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for reno that I've seen before include "Nevadan city" , "Divorce capital of Nevada" , "City in Nevada known for casinos and easy divorces" , "American city" , "US gambling resort" .)