Calm air disorientated true provider of courses (12)
I believe the answer is:
restaurateur
'provider of courses' is the definition.
'calm air disorientated true' is the wordplay.
'calm' becomes 'rest' (I've seen this before).
'air' becomes 'aura' ('aura' can be a synonym of 'air').
'disorientated' indicates an anagram.
'true' with letters rearranged gives 'teur'.
'rest'+'aura'+'teur'='RESTAURATEUR'
(Other definitions for restaurateur that I've seen before include "Owner of an eating establishment" , "Person running eating house" , "Person running establishment" , "I supply meals" , "One catering to diners" .)