Pretending to be undressed, or similar (4)
I believe the answer is:
akin
'similar' is the definition.
(similar in meaning)
'pretending to be undressed' is the wordplay.
'pretending' becomes 'faking' (faking is a kind of pretending).
'to be undressed' means to look at the middle letters (the word removes the letters which clothe it).
The middle letters of 'faking' are 'AKIN'.
'or' is the link.
(Other definitions for akin that I've seen before include "Similar in quality" , "Of similar character" , "Similar, like" , "Of a similar nature" , "Related or similiar" .)