It catches fish in the Rhone (5)
I believe the answer is:
heron
'it catches fish in' is the definition.
The definition suggests a singular noun which matches the answer.
'rhone' is the wordplay.
'rhone' anagrams to 'HERON'.
However, I'm unsure how the anagram is indicated.
'the' is the link.
Can you help me to learn more?
(Other definitions for heron that I've seen before include "Grey or white long-legged wading bird" , "Long-legged long-necked wading bird" , "One bird" , "Rhone (anag) - bird" , "Large fish-eating bird" .)