Study perfume of the valley that's getting better (12)
I believe the answer is:
convalescent
'getting better' is the definition.
(I've seen this before)
'study perfume of the valley' is the wordplay.
I cannot really understand how this works, but
'study' could be 'con' (con can informally mean to study) and 'con' is present in the answer.
'perfume' could be 'scent' (synonyms) and 'scent' is found in the answer.
'valley' could be 'vale' (synonyms) and 'vale' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'that's' acts as a link.
Can you help me to learn more?
(Other definitions for convalescent that I've seen before include "Person picking up" , "One may be showing improvement" , "getting back to normal" , "One recovering from medical treatment" , "One who's recovering" .)