Witness, removed from case, won’t peach (8)
I believe the answer is:
onlooker
'witness' is the definition.
(I've seen this before)
'removed from case won't peach' is the wordplay.
'removed from case' indicates the central letters (outside letters which encase the word are removed).
'peach' becomes 'looker' (both can mean an attractive person).
The middle letters of 'wont' are 'on'.
'on'+'looker'='ONLOOKER'
(Other definitions for onlooker that I've seen before include "One observes" , "Person watching" , "Spectator" , "He stands and watches" , "Non-participant" .)