A difficult crossword. 4ac,'Was unfaithful wife to brief deranged lord and journalist?'(9), ----O--ED; 18dn,'Abridged course for dog trainer', (6); 6dn, 'Mirage of old distracted Lilliputians & co',(7,8) must be optical illusion; but what about 17ac,'Showers of seconds,etc come mostly served with cocktails', (6,6),-t----/-L----?