Al Capone dismisses pal as a crafty type capable of sending you down the river (5)
I believe the answer is:
canoe
'down the river' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'al capone dismisses pal as a crafty type capable of sending you' is the wordplay.
I cannot quite see how this works, but
'a' could be 'an' and 'an' is located in the answer.
'of' could be 'o' and 'o' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for canoe that I've seen before include "Light paddle-propelled boat" , "River craft" , "Light boat propelled by paddle(s)" , "Small and light boat, pointed at both ends" , "A dugout" .)