Out-of-shape group of patients receiving exercise classes (6)
I believe the answer is:
warped
'out-of-shape' is the definition.
'group of patients receiving exercise classes' is the wordplay.
'group of patients' becomes 'ward' (hospital ward).
'receiving' indicates putting letters inside.
'exercise classes' becomes 'pe' (Physical Education).
'ward' going around 'pe' is 'WARPED'.
(Other definitions for warped that I've seen before include "Bent out of shape by damp or heat" , "Distorted or bent with heat" , "Twisted, bent" , "Twisted out of shape" , "Bent out of shape, usually by moisture" .)