Hail in road briefly (3)
I believe the answer is:
ave
I believe this clue is a double definition.
'hail' is the first definition.
(greeting in Latin)
'road briefly' is the second definition.
(abbreviation for avenue; 'briefly' suggests an abbreviation)
'in' is the link.
(Other definitions for ave that I've seen before include "Welcome" , "Roman greeting" , "Hail in old Rome" , "Cockney's own" , "Hail as to Caesar" .)