Doubly striking ensemble (6)
I believe the answer is:
outfit
'doubly striking ensemble' is the definition.
'outfit' can be an answer for 'ensemble' (I have seen 'Ensemble of clothes ' mean 'outfit' so perhaps 'ensemble' could also mean 'outfit'). I am not sure about the 'doubly striking' bit.
'striking ensemble' is the wordplay.
'striking' becomes 'out' (striking out is a common phrase).
'ensemble' becomes 'fit' (I can't explain this - if you can you should believe this answer much more).
'out'+'fit'='OUTFIT'
Can you help me to learn more?
(Other definitions for outfit that I've seen before include "Kit, rig-out" , "gear" , "suit" , "Equip for an enterprise" , "Ensemble of clothes" .)