Lost her new case (7)
I believe the answer is:
holster
'case' is the definition.
(I've seen this before)
'lost her new' is the wordplay.
'new' is an anagram indicator.
'lost'+'her'='losther'
'losther' anagrammed gives 'HOLSTER'.
(Other definitions for holster that I've seen before include "Holder for a hand-gun" , "Place to put piece" , "that carries a gun" , "It can carry 17 Ac" , "Pistol-case" .)