Dorothy comes back with a warty creature (4)
I believe the answer is:
toad
'warty creature' is the definition.
(I've seen this in another clue)
'dorothy comes back with a' is the wordplay.
'dorothy' becomes 'dot' (nickname for someone called Dorothy).
'comes back' says the letters should be written in reverse.
'with' means one lot of letters goes inside another.
'dot' back-to-front is 'tod'.
'tod' going around 'a' is 'TOAD'.
(Other definitions for toad that I've seen before include "Common amphibian" , "Wind in Willows motorist" , "Contemptible person" , "Warty amphibian" , "A loathsome person" .)