Self-aggrandising Scot taking in English girl and Arab (12)
I believe the answer is:
megalomaniac
'self-aggrandising scot taking in english girl and arab' is the definition.
I can't judge whether this definition defines the answer.
'scot taking in english girl and arab' is the wordplay.
'scot' becomes 'mac' (many Scottish surnames begin with Mac).
'taking in' means one lot of letters goes inside another.
'english girl' becomes 'egal' (I can't justify this - if you can you should give a lot more credence to this answer).
'and' means one lot of letters go next to another.
'arab' becomes 'Omani' (someone from Oman).
'egal'+'omani'='egalomani'
'mac' going around 'egalomani' is 'MEGALOMANIAC'.
Can you help me to learn more?
(Other definitions for megalomaniac that I've seen before include "Power-mad individual" , "Act of controlling by force" , "Pathological egotist" , "Person with delusions of power" , "One thinking he is great" .)