Treatment misrepresented as hippy theory (13)
I believe the answer is:
physiotherapy
'treatment' is the definition.
(physiotherapy is a kind of treatment)
'misrepresented as hippy theory' is the wordplay.
'misrepresented' indicates an anagram.
'as'+'hippy'+'theory'='ashippytheory'
'ashippytheory' with letters rearranged gives 'PHYSIOTHERAPY'.
(Other definitions for physiotherapy that I've seen before include "Treatment of illness or injury using massage, exercise etc" , "Manipulative medical treatment" .)