Rotter left inside to get dressed (4)
I believe the answer is:
clad
'dressed' is the definition.
(to be clad in something is to be dressed in it)
'rotter left inside' is the wordplay.
'rotter' becomes 'cad' (a cad is a dishonourable person).
'left' becomes 'l' (common abbreviation).
'inside' indicates putting letters inside.
'cad' placed around 'l' is 'CLAD'.
'to get' acts as a link.
(Other definitions for clad that I've seen before include "Decked" , "Dressed" , "Wearing" , "Clothed, covered" , "Invested" .)