Bellow beginning to race with paddle (4)
I believe the answer is:
roar
'bellow' is the definition.
('roar' can be a synonym of 'bellow')
'beginning to race with paddle' is the wordplay.
'beginning to' indicates taking the first letters.
'with' says to put letters next to each other.
'paddle' becomes 'oar' (I've seen this before).
The first letter of 'race' is 'r'.
'r'+'oar'='ROAR'
(Other definitions for roar that I've seen before include "Great cry" , "Shout loudly" , "Lion's noise" , "Loud cry" , "engine noise" .)