Kills 40 on board with a single arrow? (4)
I believe the answer is:
tops
'kills' is the definition.
'40 on board with a single arrow?' is the wordplay.
I cannot really understand how this works, but
'on' could be 'to' and 'to' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for tops that I've seen before include "The best" , "spinners" , "Surpasses; toys" , "Max - spinning toys" , "Goes beyond" .)