Judge gets a rare snack next to river (7)
I believe the answer is:
arbiter
'judge' is the definition.
(thesaurus)
'a rare snack next to river' is the wordplay.
'rare' becomes 'r' (listed by Oxford Dictionary of Abbreviations).
'snack' becomes 'bite' ('bite' can be a synonym of 'snack'**).
'next to' says to put letters next to each other.
'river' becomes 'r'.
'a'+'r'+'bite'+'r'='ARBITER'
'gets' acts as a link.
(Other definitions for arbiter that I've seen before include "One has the authority to resolve disputes" , "Rear bit (anag.)" , "One settling disputes" , "Judge - mediator" , "Judge, adjudicator" .)