Working group arrive with German note secured (9)
I believe the answer is:
committee
'working group' is the definition.
(I've seen this before)
'arrive with german note secured' is the wordplay.
'arrive' becomes 'come' (coming is a kind of arriving).
'with german' becomes 'mit'.
'note' becomes 'te' (**).
'secured' is an insertion indicator.
'mit'+'te'='mitte'
'come' placed around 'mitte' is 'COMMITTEE'.
(Other definitions for committee that I've seen before include "Panel set up for a purpose" , "Group of people selected to run things" , "Group selected to undertake certain duties" , "Executive group" , "Board" .)