Where one might find desire to perform back to back (2,4)
I believe the answer is:
in turn
'back' is the definition.
Both the answer and definition are adverbs. Perhaps you can see an association between them that I don't see?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for in turn that I've seen before include "not out of place" , "orderly treatment" , "One after another" , "a succession of things happen" , "in an orderly fashion" .)