Costume seen immediately following tango? (7)
I believe the answer is:
uniform
I believe this is a double definition.
'costume' is the first definition.
(both can mean clothing)
'seen immediately following tango?' is the second definition.
(uniform comes after tango in the phonetic alphabet)
(Other definitions for uniform that I've seen before include "Regular - military attire" , "Always the same, unvarying." , "Dress it up (7)" , "Regimentals" , "Military wear" .)