Room for service personnel in a port (7)
I believe the answer is:
messina
'port' is the definition.
(I've seen this before)
'room for service personnel' is the wordplay.
'room' becomes 'mess' (mess is a kind of room).
'for' is a charade indicator (letters next to each other).
'service personnel' becomes 'ina' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'mess'+'ina'='MESSINA'
'in a' acts as a link.
Can you help me to learn more?
(Other definitions for messina that I've seen before include "Sicilian port" , "City in Sicily" .)