One saving scarlet Irish woman who ingested ecstasy (8)
I believe the answer is:
'woman who ingested ecstasy' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe there's an association between them I don't understand?
'one saving scarlet irish' is the wordplay.
'one' becomes 'me' (a setter might use 'one' to humourously mean 'me').
'saving' means one lot of letters goes inside another (inserted letters are kept or saved).
'scarlet' becomes 'red' (synonyms).
'irish' becomes 'eer' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'me' placed into 'redeer' is 'REDEEMER'.
Can you help me to learn more?
(Other definitions for redeemer that I've seen before include "Mere deer for the saviour" , "One who saves (another) from sin" , "One who delivers (people) from sin" , "Christ, who saved us from damnation" , "One saving another from sin" .)