Hold up English dress (4)
I believe the answer is:
'dress' is the definition.
(I know that robe is a type of gown)
'hold up english' is the wordplay.
'hold up' becomes 'rob' (as in holding up a bank).
'english' becomes 'e' (abbreviation).
(Other definitions for robe that I've seen before include "Old cloak for Boer" , "Dressing-gown" , "Christening garment" , "Clerical garment" , "Any loose flowing garment" .)