Dog that visited Oz (4)
I believe the answer is:
toto
'dog that visited oz' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for toto that I've seen before include "Dorothy's dog in The Wizard of Oz" , "Famous film dog" , "member of the 5d band" , "[FRIEND OF DOROTHY]" .)