Gets tango with energy — and speed (5)
I believe the answer is:
haste
'speed' is the definition.
(I know that haste is a type of speed)
'gets tango with energy' is the wordplay.
'gets' becomes 'has' ('have' can be a synonym of 'get').
'tango' becomes 'T' (phonetic alphabet: alpha, bravo, charlie etc.).
'with' is a charade indicator (letters next to each other).
'energy' becomes 'e' (physics symbol as in E=mc2).
'has'+'t'+'e'='HASTE'
'and' is the link.
(Other definitions for haste that I've seen before include "Rushing (but with less speed?)" , "go at speed" , "Speediness or rush" , "Possible cause of careless mistakes?" , "The more of it, the less speed sometimes" .)