Do well to answer verbally. "What is XX plus XX?" (5)
I believe the answer is:
excel
'do well' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for excel that I've seen before include "cap" , "Perform exceptionally well" , "Be highly proficient" , "Do really well, outshine others" , "Top" .)