Neither looking good nor feeling well (5)
I believe the answer is:
seedy
'well' is the definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I don't see?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for seedy that I've seen before include "Unseemly" , "Off-colour" , "sickly" , "Unpleasant" , "Raspberry jam might be" .)