One paid for knotting ropes pointlessly? (3)
I believe the answer is:
pro
'one paid for' is the definition.
'pro' can be an answer for 'for' (I've seen this before). I am not certain of the 'one paid' bit.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for pro that I've seen before include "For; non-amateur" , "Favouring the professional" , "Professional; advantage" , "Golfer" , "Athelete who plays for pay" .)