Gazes at the sound of flight (6)
I believe the answer is:
stares
'gazes' is the definition.
('stare' can be a synonym of 'gaze')
'the sound of flight' is the wordplay.
'the sound of' indicates a 'sounds like' (homophone) clue.
'flight' becomes 'stairs' (I've seen this before).
'stairs' is a homophone of 'STARES'.
'at' acts as a link.
(Other definitions for stares that I've seen before include "Long gazes" , "Assert with long looks" , "Looks lengthily at" , "Looks fixedly" , "Looks hard" .)