Axe seen in helicopter (7)
I believe the answer is:
chopper
This clue is a double definition.
'axe' is the first definition.
(I've seen this before)
'helicopter' is the second definition.
(synonyms)
'seen in' acts as a link.
(Other definitions for chopper that I've seen before include "that's used by a lumberjack" , "An informal helicopter, or an axe" , "Small axe" , "Lizzie Borden" , "Butcher's cleaver" .)