With the contents removed - completely (6,3)
I believe the answer is:
inside out
'completely' is the definition.
(thesaurus)
'with the contents removed' is the wordplay.
'with' says to put letters next to each other.
'the contents' becomes 'inside' (I can't explain this - if you can you should give a lot more credence to this answer).
'removed' becomes 'out' (taken out).
'inside' put next to 'out' is 'INSIDE-OUT'.
Can you help me to learn more?
(Other definitions for inside out that I've seen before include "how expert knows his trade?" , "Thoroughly" , "exposing the wrong face?" , "Turned to show the inner surface" , "comprehensively" .)