Like a costly victory (7)
I believe the answer is:
pyrrhic
'like a costly victory' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pyrrhic that I've seen before include "A victory won at such great cost that it's not a triumph" , "A victory won at too great a cost to the victor" , "This victory comes at too great a price" , "Such a victory as bad as defeat" , "This kind of victory is too costly" .)