Extremely anxious captain to abort take off (6)
I believe the answer is:
ascend
'take off' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for ascend that I've seen before include "Move upwards" , "Take off" , "Climb, rise" , "Gain altitude" , "Mount" .)