Flier sees V1 in two areas by hill (7)
I believe the answer is:
aviator
'flier' is the definition.
(I know that flier can be written as aviator)
'v1 in two areas by hill' is the wordplay.
'va' becomes 'v'.
'in' is an insertion indicator.
'two areas' becomes 'aia' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'by' is a charade indicator (letters next to each other).
'hill' becomes 'tor' (tor is a kind of hill).
'v' going inside 'aia' is 'avia'.
'avia'+'tor'='AVIATOR'
'sees' acts as a link.
Can you help me to learn more?
(Other definitions for aviator that I've seen before include "Airman" , "Woman in a flying machine" , "Flyer, pilot" , "One flying aircraft" , "Pilot; style of sunglasses" .)