Double-action carrier (8)
I believe the answer is:
suitcase
'carrier' is the definition.
'double-action' is the wordplay.
'double' becomes 'suit' (I can't justify this - if you can you should give a lot more credence to this answer).
'action' becomes 'case' (synonyms).
'suit'+'case'='SUITCASE'
Can you help me to learn more?
(Other definitions for suitcase that I've seen before include "Pack it to travel {8}" , "Item of luggage" , "Traveling bag" , "Piece of luggage" , "Form of luggage" .)