Case ends in outcome against you and I (4)
I believe the answer is:
etui
'case' is the definition.
(case for needlework equipment)
'ends in outcome against you and i' is the wordplay.
'ends in' says to take the final letters.
'and' means one lot of letters go next to another.
The final letters of 'outcome against you' are 'etu'.
'etu'+'i'='ETUI'
(Other definitions for etui that I've seen before include "box" , "Small French case" , "Ornamental ladies' bag for small articles" , "Case containing sharp objects" , "Small sewing bag" .)