What those who are busy boxing do (6)
I believe the answer is:
encase
'do' is the definition.
Although both the answer and definition are verbs in their base form, I cannot see how one could define the other.
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for encase that I've seen before include "Wrap" , "Cover completely" , "Enclose, cover" , "Frame" , "Cover with close-fitting surround" .)