Dress I am returning with wrong mark in it (4)
I believe the answer is:
maxi
'dress' is the definition.
(I've seen this before)
'i am returning with wrong mark in it' is the wordplay.
'i am' becomes 'I'm' (contraction).
'returning' says the letters should be written backwards.
'with wrong mark' becomes 'ax' (I am not sure about this - if you are sure you should believe this answer much more).
'in it' means one lot of letters goes inside another.
'im' reversed gives 'mi'.
'mi' enclosing 'ax' is 'MAXI'.
Can you help me to learn more?
(Other definitions for maxi that I've seen before include "full length garment" , "racing yacht" , "what garment is not revealing?" , "Long skirt of coat" , "Relatively long skirt" .)