Small overnight bag (6)
I believe the answer is:
valise
'small overnight bag' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for valise that I've seen before include "Overnight case" , "Small overnight bag" , "A small suitcase for Leavis" , "Elvis A? (anag)" , "Small travelling bag or suitcase" .)