For instance, topless dress is way out (6)
I believe the answer is:
egress
'way out' is the definition.
(thesaurus)
'for instance topless dress' is the wordplay.
'for instance' becomes 'eg' ('e.g.' can be a synonym of 'for instance').
'topless' means to remove the first letter.
'dress' with its initial letter taken away is 'ress'.
'eg'+'ress'='EGRESS'
'is' acts as a link.
(Other definitions for egress that I've seen before include "Emergence, coming out" , "Action of going out" , "Issue" , "Act of exiting" , "The act of going out" .)