Fed up with flying? (7)
I believe the answer is:
airsick
'fed' is the definition.
The answer and definition are not the same part of speech. However, past participle verbs and adjectives can occasionally mean the same thing.
'up with flying?' is the wordplay.
'up' becomes 'sick' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'with' means one lot of letters go next to another.
'flying?' becomes 'air' (flying is a kind of air).
'sick' put after 'air' is 'AIRSICK'.
Can you help me to learn more?
(Other definitions for airsick that I've seen before include "Nauseous when flying" , "Unwell when flying" , "Nauseous in flight" , "Ill when flying" .)