No heroics involved capturing river animal (10)
I believe the answer is:
rhinoceros
'animal' is the definition.
(I've seen this before)
'no heroics involved capturing river' is the wordplay.
'involved' indicates an anagram (involved can mean confusing or complex).
'capturing' indicates putting letters inside.
'river' becomes 'r' (abbreviation for river).
'no'+'heroics'='noheroics'
'noheroics' anagrammed gives 'rhinoceos'.
'rhinoceos' enclosing 'r' is 'RHINOCEROS'.
(Other definitions for rhinoceros that I've seen before include "Large, thick-skinned ungulate" , "Horny character" , "Horned mammal" , "used to be wild and woolly" , "Native of Africa" .)