Most uninspiring airport tax originally (7)
I believe the answer is:
dullest
'most uninspiring airport tax originally' is the definition.
I can't judge whether this definition defines the answer.
'uninspiring airport tax originally' is the wordplay.
'uninspiring' becomes 'dull' (I've seen this before).
'airport' becomes 'es' (I can't explain this - if you can you should give a lot more credence to this answer).
'originally' indicates taking the first letters.
The initial letter of 'tax' is 't'.
'dull'+'es'+'t'='DULLEST'
Can you help me to learn more?
(Other definitions for dullest that I've seen before include "Most insensitive" , "that's not at all interesting" , "Least shiny" , "Most unintelligent" , "Least interesting" .)