Fail to declare what runner gives you to carry (5)
I believe the answer is:
baton
'carry' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'fail to declare what runner gives you' is the wordplay.
I cannot really understand how this works, but
'to' is present in the answer.
The remaining letters 'ban' 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).
'to' is the link.
Can you help me to learn more?
(Other definitions for baton that I've seen before include "Club, stick" , "Controller of players" , "Conductor's rod" , "Short rod (that can be passed!)" , "Light wand" .)