Point to it returning in maps as a lost island (8)
I believe the answer is:
atlantis
'a lost island' is the definition.
(I've seen this before)
'point to it returning in maps' is the wordplay.
'point' becomes 'n' (N is an example).
'to' means one lot of letters go next to another (I've seen this in other clues).
'returning' is a reversal indicator.
'in' indicates putting letters inside.
'maps' becomes 'atlas' (printed collection of maps).
'n' after 'it' is 'itn'.
'itn' back-to-front is 'nti'.
'nti' going within 'atlas' is 'ATLANTIS'.
'as' is the link.
(Other definitions for atlantis that I've seen before include "Legendary kingdom overwhelmed by the sea" , "Legendary island engulfed by the sea" , "Fabled lost island" , "In Greek legend, beautiful island lost in the sea" , "Legendary vanished island - mythical place" .)