Labelling to get sign of approval, say, on outside of container (9)

'labelling' is the definition.
(ticketing can mean putting labels on things)

'sign of approval say on outside of container' is the wordplay.
'sign of approval' becomes 'tick' (I've seen this before).
'say' becomes 'eg' (both can mean for example).
'on outside of' means one lot of letters goes inside another.
'container' becomes 'tin' (tin is a kind of container).
'eg' enclosing 'tin' is 'eting'.
'tick'+'eting'='TICKETING'

'to get' is the link.