Imagines the doctor has the same disorder (6)
I believe the answer is:
dreams
'imagines' is the definition.
(dreaming is a kind of imagining)
'doctor has the same disorder' is the wordplay.
'doctor' becomes 'dr' (abbreviation).
'has' is a charade indicator (letters next to each other).
'disorder' indicates an anagram (a disordered version of the letters).
'same' is an anagram of 'eams'.
'dr'+'eams'='DREAMS'
'the' is the link.
(Other definitions for dreams that I've seen before include "'We are such stuff / As dreams are made on' (The Tempest)" , "Fantasies; fantasises" , "Thoughts and visions during sleep" , "Fancies" , "Fantasy ambitions" .)