Scatty, rather like Dorothy (5)
I believe the answer is:
dotty
'scatty' is the definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I don't see?
'rather like dorothy' is the wordplay.
I cannot really see how this works, but
'like' could be 'y' (similar in meaning) and 'y' is present in the answer.
'dorothy' could be 'dot' (nickname for someone called Dorothy) and 'dot' is located in the answer.
A single letter 't' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for dotty that I've seen before include "Barking" , "Slightly mad (colloq.)" , "Bonkers; speckled" , "Slightly crazy" , "Feeble-minded" .)