Eremitic Levi's ulcers discovered when standing up (9)
I believe the answer is:
reclusive
'eremitic' is the definition.
Both the answer and definition are adjectives. Perhaps you can see an association between them that I can't see?
'levi's ulcers discovered when standing up' is the wordplay.
'discovered' indicates a hidden word (remove the letters covering the answer in the clue).
'when standing up' says the letters should be written backwards (in a down clue, letters go up).
'evisulcer' is hidden within 'levis ulcers'.
'evisulcer' in reverse letter order is 'RECLUSIVE'.
Can you help me to learn more?
(Other definitions for reclusive that I've seen before include "Hermit-like" , "Solitary" , "retiring" .)