A blade used by crew avoiding river animal (4)
I believe the answer is:
anoa
'animal' is the definition.
(anoa is a type of buffalo)
'a blade used by crew avoiding river' is the wordplay.
I cannot quite see how this works, but
'a' could be 'an' and 'an' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for anoa that I've seen before include "Wild ox" , "water-buffalo" .)