Slowly undressing, lady bags Dior (6)
I believe the answer is:
adagio
'slowly' is the definition.
(I've seen this before)
'lady bags dior' is the wordplay.
'lady' becomes 'ada'.
'bags dior' becomes 'gio' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ada'+'gio'='ADAGIO'
'undressing' is the link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for adagio that I've seen before include "Leisurely, musically speaking" , "leisurely movement" , "Slow piece of music" , "develops slowly" , "Slow movement (music)" .)