One devout woman, old-fashioned, overwhelmed (9)
I believe the answer is:
inundated
'overwhelmed' is the definition.
(I've seen this in another clue)
'one devout woman old-fashioned' is the wordplay.
'one' becomes 'i' (Roman numeral).
'devout woman' becomes 'nun' (I've seen this before).
'old fashioned' becomes 'dated' (I've seen this before).
'i'+'nun'+'dated'='INUNDATED'
(Other definitions for inundated that I've seen before include "Deluged" , "flooded" , "drowned" .)