Obsessive is, say, pointing up a source of relief (9)
I believe the answer is:
analgesia
'relief' is the definition.
(I have seen 'Relief of pain ' mean 'analgesia' so perhaps 'relief' could also mean 'analgesia')
'obsessive is say pointing up a source' is the wordplay.
I cannot quite see how this works, but
'obsessive' could be 'anal' (anal can mean obsessed with order) and 'anal' is located in the answer.
'a' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'of' is the link.
Can you help me to learn more?
(Other definitions for analgesia that I've seen before include "Absence of pain" , "Inability to feel pain" , "Loss of pain" , "result of medication?" , "Painlessness" .)