Slightly eccentric (5)
(Other definitions for dotty that I've seen before include "Bonkers; speckled" , "like a Dalmatian?" , "Slightly mad (colloq.)" , "Silly; crazy" , "Slightly crazy" .)
(Other definitions for potty that I've seen before include "Foolish" , "Daft (informal)" , "Bonkers" , "Mad" , "sort of chamber?" .)
(Other definitions for crackers that I've seen before include "Yanks open these" , "they may be on the table at Christmas" , "full of bad jokes at Yuletide?" , "and some others touched" , "Crazy - (American) biscuits" .)