Best rebuttal (5)
I believe the answer is:
Here is my best explanation:
This might be a double definition.
'best' is the first definition.
(I've seen this before)
'rebuttal' is the second definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
(Other definitions for worst that I've seen before include "the pits", "Lowest of the low", "Direst", "Most severe", "Strangely, best", "Get better of; very bad", "Far from the best - defeat", "Beat", "Most badly" and "Most inferior or evil".)