Light-fingered types with permission to interrupt meals (3,6)
I believe the answer is:
tea leaves
'light-fingered types' is the definition.
(tea leaf is Cockney rhyming slang for thief)
'permission to interrupt meals' is the wordplay.
'permission' becomes 'leave' (leave is permission or authorisation).
'to interrupt' indicates putting letters inside.
'meals' becomes 'teas' (tea is a kind of meal).
'leave' put within 'teas' is 'TEA-LEAVES'.
'with' is the link.
(Other definitions for tea leaves that I've seen before include "Source of drink" , "Thieves" , "found among the dregs" , "Magpies" .)