Entry ID when menus are encrypted (8)
I believe the answer is:
username
'entry id' is the definition.
'menus are encrypted' is the wordplay.
'encrypted' indicates an anagram.
'menus'+'are'='menusare'
'menusare' is an anagram of 'USERNAME'.
'when' is the link.
(Other definitions for username that I've seen before include "Login ID" , "Online identity" , "Person's computer ID" , "Electronic identity" , "Log in identifier" .)