Check next to one river and another for animals (8)
I believe the answer is:
reindeer
'animals' is the definition.
(I've seen this before)
'check next to one river and another' is the wordplay.
'check' becomes 'rein' (both can mean to control or limit).
'next' means one lot of letters go next to another (I've seen this in other clues).
'to one river' becomes 'dee' (River Dee).
'and' is a charade indicator (letters next to each other).
'another' becomes 'r' (I've seen this in other clues).
'rein'+'dee'+'r'='REINDEER'
'for' is the link.
(Other definitions for reindeer that I've seen before include "Rudolph, say" , "Domesticated animals" , "Antlered animal" , "Animal from 1 across" , "Animal in dire Erne" .)