A mental disorder involving distress but neither delusions nor hallucinations (8)
I believe the answer is:
neurosis
(Other definitions for neurosis that I've seen before include "Mild mental illness not caused by an organic disease" , "So insure against the nervous disorder" , "Mental disorder of resinous origin" , "Mild mental problem" , "Resinous (anag) -- unspecific personality disturbance" .)