Odour rising from Sam or Alison (5)
I believe the answer is:
aroma
'odour' is the definition.
(synonyms)
'rising from sam or alison' is the wordplay.
'rising' is a reversal indicator (going up in a down clue).
'from' indicates a hidden word.
'amora' is hidden in the letters of 'sam or alison'.
'amora' backwards is 'AROMA'.
(Other definitions for aroma that I've seen before include "Distinctive scent" , "Food fragrance" , "Pervasive quality" , "Test of knowledge" , "Strong smell" .)