Approval when shipped (6)
I believe the answer is:
assent
'approval' is the definition.
(I've seen this in another clue)
'when shipped' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'shipped' becomes 'sent' ('send' can be a synonym of 'ship').
'as'+'sent'='ASSENT'
(Other definitions for assent that I've seen before include "Agree, acquiesce" , "Nod" , "Consent or approval" , "Give consent" , "Say yes" .)