Sharp odour rising over skivvy (9)
I believe the answer is:
observant
'sharp' is the definition.
(thesaurus)
'odour rising over skivvy' is the wordplay.
'odour' becomes 'B.O.' (B.O. is an example).
'rising' says the letters should be written backwards (letters written upwards in a down clue).
'over skivvy' becomes 'servant' (I am not sure about this - if you are sure you should believe this answer much more).
'bo' reversed gives 'ob'.
'ob'+'servant'='OBSERVANT'
Can you help me to learn more?
(Other definitions for observant that I've seen before include "following religious practices" , "aware of surroundings" , "Good at noticing" , "Quick to notice things" , "adhering to religious practices" .)