Animal taking over English river's eating tons (5)
I believe the answer is:
otter
'animal' is the definition.
(thesaurus)
'taking over english river's eating tons' is the wordplay.
'taking over' becomes 'ot' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'english' becomes 'e' (abbreviation).
'river' becomes 'r'.
'eating' means one lot of letters goes inside another.
'tons' becomes 't'.
'ot'+'e'+'r'='oter'
'oter' enclosing 't' is 'OTTER'.
Can you help me to learn more?
(Other definitions for otter that I've seen before include "Freshwater carnivorous mammal with webbed and clawed feet" , "Something furry" , "furry animal" , "bad-tempered little beast" , "Aquatic weasel-like mammal" .)