Harmful refusal by native Americans to swap tips (7)
I believe the answer is:
noxious
'harmful' is the definition.
(similar in meaning)
'refusal by native americans to swap tips' is the wordplay.
I cannot really understand how this works, but
'refusal' could be 'no' and 'no' is found within the answer.
'by' could be 'x' (2 by 4 is 2 x 4) and 'x' is located in the answer.
'americans' could be 'us' (United States) and 'us' is found in the answer.
The remaining letters 'io' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for noxious that I've seen before include "Pernicious" , "Harmful, toxic" , "Disgusting" , "bad for you" , "Harmful, poisonous" .)