Animal cry beginning to resound over a river (4)
I believe the answer is:
roar
'animal cry' is the definition.
'roar' can be an answer for 'cry' (roar is a kind of cry). I am not certain of the 'animal' bit.
'beginning to resound over a river' is the wordplay.
'beginning to' suggests taking the first letters.
'river' becomes 'r' (abbreviation).
The initial letters of 'resound over' is 'ro'.
'ro'+'a'+'r'='ROAR'
Can you help me to learn more?
(Other definitions for roar that I've seen before include "Make a loud noise" , "Make loud angry sound like lion" , "The __ of the Greasepaint -- The Smell of the Crowd (1964 musical)" , "Lion's noise" , "Lion's call" .)