Clan from Tiber spread out (5)
I believe the answer is:
tribe
'clan' is the definition.
(I know that clan can be written as tribe)
'tiber spread out' is the wordplay.
'spread out' indicates anagramming the letters (I've seen 'spreading out' mean this).
'tiber' is an anagram of 'TRIBE'.
'from' acts as a link.
(Other definitions for tribe that I've seen before include "Extended family group" , "Racial group living under chief" , "Group of people with a common culture" , "Traditional social group" , "A set or class of people, may be primitive" .)