Monkey drops in West Country river (5)
I believe the answer is:
tamar
'west country river' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for tamar that I've seen before include "Devon-Cornwall boundary river" , "River of SW England" , "flower" , "woman who posed as a prostitute" , "Plymouth river" .)