Extremely healthy or just all right (4,4)
I believe the answer is:
very well
I believe this is a double definition.
'extremely healthy' is the first definition.
(I've seen this before)
'all right' is the second definition.
(synonyms)
'or just' is the link.
(Other definitions for very well that I've seen before include "Yes, I suppose so" , "said by some to be obliging" , "I guess so" , "okay" , "If you say so - in extremely good health" .)