Kink: pot sent back (4)
I believe the answer is:
loop
'kink' is the definition.
The definition and answer can be both shapes as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'pot sent back' is the wordplay.
'pot' becomes 'pool' (both can mean a shared resource of money).
'sent back' says the letters should be written in reverse.
'pool' reversed gives 'LOOP'.
Can you help me to learn more?
(Other definitions for loop that I've seen before include "Oval or U-shaped coil or bend" , "Aerobatic manoeuvre" , "going round" , "Complete circuit; encircle" , "I cross myself" .)