She has now returned to the valley (6)
I believe the answer is:
glenda
'she' is the definition.
'now returned to the valley' is the wordplay.
'now' becomes 'AD' (AD, Anno Domini, as opposed to BC, Before Christ).
'returned' shows that the letters should be reversed in order.
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'the valley' becomes 'glen' (glen is a kind of valley).
'ad' reversed gives 'da'.
'da' after 'glen' is 'GLENDA'.
'has' acts as a link.
(Other definitions for glenda that I've seen before include "Girl" , "-- Jackson, actress and former MP" , "- - Jackson, Hampstead MP" , "--- Jackson, Br. actress" .)