Concerning Anne dancing the tango (5)
I believe the answer is:
anent
'concerning' is the definition.
(I've seen this before)
'anne dancing the tango' is the wordplay.
'dancing' indicates an anagram.
'the tango' becomes 'T' (phonetic alphabet: alpha, bravo, charlie etc.).
'anne' anagrammed gives 'anen'.
'anen'+'t'='ANENT'
(Other definitions for anent that I've seen before include "Concerning (archaic)" , "Concerned with" , "About (Scottish)" .)