Haughty claim of fairy to dismiss mostly (9)
I believe the answer is:
imperious
'haughty' is the definition.
(I know that haughty can be written as imperious)
'claim of fairy to dismiss mostly' is the wordplay.
'claim of fairy' becomes 'imperi' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'to dismiss' becomes 'oust' (I've seen this in another clue).
'mostly' means to remove the last letter (most but not all of the word).
'oust' with its last letter removed is 'ous'.
'imperi'+'ous'='IMPERIOUS'
Can you help me to learn more?
(Other definitions for imperious that I've seen before include "high-handed" , "Haughty - domineering" , "Bossy" , "Arrogant, domineering" .)