Mike queasy on part of flight, it's routine (9)
I believe the answer is:
treadmill
'routine' is the definition.
(treadmill can mean a boring job or routine)
'mike queasy on part of flight' is the wordplay.
'mike' becomes 'M' (phonetic alphabet: alpha, bravo, charlie etc.).
'queasy' becomes 'i'll' (similar in meaning).
'on' means one lot of letters go next to another.
'part of flight' becomes 'tread' (I've seen this before).
'm'+'ill'='mill'
'mill' put after 'tread' is 'TREADMILL'.
'it's' is the link.
(Other definitions for treadmill that I've seen before include "Walking or running exercise device" , "Endlessly tedious job" , "tedious work" , "Boring routine; old rotary device" , "Wheel turned by walking animals or people" .)