On the other side of the page (8)
I believe the answer is:
overleaf
'on the other side of the page' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for overleaf that I've seen before include "On the other side of the page" , "next page - with 12a" , "What vigorous 26 [TREE] may do" , "On the page's other side" , "On the next even-numbered page" .)