In Ireland, a deceived girl (7)
I believe the answer is:
donegal
'in ireland' is the definition.
The definition suggests a singular noun which matches the answer.
'a deceived girl' is the wordplay.
'a deceived' becomes 'done' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'girl' becomes 'gal' ('gal' can be a synonym of 'girl').
'done'+'gal'='DONEGAL'
Can you help me to learn more?
(Other definitions for donegal that I've seen before include "Ireland's northmost county" , "Northernmost Irish county" , "part of Ireland" , "Lean dog (anag) - Irish county" , "County of NW Ireland" .)