Arrived back with a robe (4)
I believe the answer is:
toga
'robe' is the definition.
(I have seen 'Roman robe ' mean 'toga' so perhaps 'robe' could also mean 'toga')
'arrived back with a' is the wordplay.
'arrived' becomes 'got' ('get' can be a synonym of 'arrive').
'back' shows that the letters should be reversed in order.
'with' means one lot of letters go next to another.
'got' in reverse letter order is 'tog'.
'tog'+'a'='TOGA'
(Other definitions for toga that I've seen before include "Roman clothing" , "Ancient Roman garment" , "Roman tunic" , "Graph's y value" , "Old Roman gown" .)