Outrageous old woman drained nurses (8)
I believe the answer is:
flagrant
'outrageous' is the definition.
(flagrant can mean outrageous or blatant)
'old woman drained nurses' is the wordplay.
'old woman' becomes 'gran' (short for grandmother).
'drained' becomes 'flat' (I can't justify this - if you can you should give a lot more credence to this answer).
'nurses' is an insertion indicator (nurse can mean to hold onto or harbour).
'gran' put inside 'flat' is 'FLAGRANT'.
Can you help me to learn more?
(Other definitions for flagrant that I've seen before include "'Conspicuous, glaring (8)'" , "Barefaced" , "Of unconcealed outrageousness" , "Patent" , "notorious" .)