Shout for right paddle (4)
I believe the answer is:
'shout' is the definition.
(I know that roar is a type of shout)
'for right paddle' is the wordplay.
'right' suggests the final letters (the letter on the right of the word).
'paddle' becomes 'oar' (I've seen this before).
The final letter of 'for' is 'r'.
(Other definitions for roar that I've seen before include "Loud noise of angry bull" , "Shout loudly" , "Deep-throated cry" , "Loud cry" , "Lion's call" .)