Sources of words given by new user - a hit (8)
I believe the answer is:
thesauri
'sources of words' is the definition.
(plural of thesaurus)
'new user a hit' is the wordplay.
'new' indicates anagramming the letters.
'user'+'a'+'hit'='userahit'
'userahit' with letters rearranged gives 'THESAURI'.
'given by' acts as a link.
(Other definitions for thesauri that I've seen before include "References" , "they may aid writers" , "Word books" , "Reference works providing synonyms" , "Word founts" .)