New tribe flowing through Rome (5)
I believe the answer is:
tiber
'flowing through rome' is the definition.
The definition suggests a singular noun which matches the answer.
'new tribe' is the wordplay.
'new' is an anagram indicator.
'tribe' with letters rearranged gives 'TIBER'.
Can you help me to learn more?
(Other definitions for tiber that I've seen before include "Italian banker" , "River entering the Mediterranean at Ostia" , "River of Rome" , "Roman river" , "Italian river with Ostia at its mouth" .)