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' going around 'l' is 'CLAD'.
'to get' is the link.
(Other definitions for clad that I've seen before include "Decked" , "Dressed" , "Wearing" , "Clothed, covered" , "Invested" .)