Treatment providing cure - cut up an eccentric (11)
I believe the answer is:
'treatment' is the definition.
(acupuncture is a kind of treatment)
'cure cut up an eccentric' is the wordplay.
'eccentric' indicates anagramming the letters.
'curecutupan' with letters rearranged gives 'ACUPUNCTURE'.
'providing' is the link.
(Other definitions for acupuncture that I've seen before include "Complementary medicine using needles" , "Method of treatment with needles" , "Alternative treatment using needles" , "Pain relief by needles" , "Form of alternative medicine" .)