Thus, one in airport's what you seek here (9)
I believe the answer is:
solutions
'what you seek here' is the definition.
(what you seek as a solver)
'thus one in airport's' is the wordplay.
'thus' becomes 'so' ('so' can be a synonym of 'thus').
'one' becomes 'i' (Roman numeral).
'in' indicates putting letters inside.
'airport's' becomes 'lutons' (London Luton Airport).
'i' put into 'lutons' is 'lutions'.
'so'+'lutions'='SOLUTIONS'
(Other definitions for solutions that I've seen before include "Homogeneous mixtures" , "76 are required here" , "Correct answers to puzzles" , "Answers sought or found" , "Correct answers to clues" .)