Back and __ (to and fro) (5)
I believe the answer is:
forth
(Other definitions for forth that I've seen before include "Onward; the Firth of - -" , "(Go) away" , "Onward direction" , "Water" , "Edinburgh's river" .)
I believe the answer is:
forth
(Other definitions for forth that I've seen before include "Onward; the Firth of - -" , "(Go) away" , "Onward direction" , "Water" , "Edinburgh's river" .)