Car seat is adapted for internal flight (9)
I believe the answer is:
staircase
'internal flight' is the definition.
'staircase' can be an answer for 'flight' (a flight of stairs). I'm not certain of the 'internal' bit.
'car seat is adapted' is the wordplay.
'adapted' is an anagram indicator.
'car'+'seat'+'is'='carseatis'
'carseatis' with letters rearranged gives 'STAIRCASE'.
'for' is the link.
Can you help me to learn more?
(Other definitions for staircase that I've seen before include "Route between floors" , "exited via this?" , "part of the mansion?" , "Group of joined locks on a canal" , "Flight of steps" .)