Frodo urgently hides aroma (5)
I believe the answer is:
odour
'aroma' is the definition.
(I know that aroma can be written as odour)
'frodo urgently hides' is the wordplay.
'hides' indicates a hidden word.
'ODOUR' is hidden in the letters of 'frodo urgently'.
(Other definitions for odour that I've seen before include "Small, aroma" , "Distinctive smell" , "Pong" , "Aroma, smell" , "Stink" .)