Dress code’s solution perhaps for one often depressed (5,3)
I believe the answer is:
shift key
'one often depressed' is the definition.
(button on a keyboard often pressed down)
'dress code's solution perhaps' is the wordplay.
'dress' becomes 'shift' (shift is a kind of dress).
'code's solution perhaps' becomes 'key' (the rules unlocking a code).
'shift'+'key'='SHIFT-KEY'
'for' acts as a link.
(Other definitions for shift key that I've seen before include "Typewriter feature, used to achieve capital letters" , "One pressed to find capital" , "Press it to type capitals" , "Button on keyboard for capitals" , "means of capital production" .)