Stunt nowadays during flight (8)
I believe the answer is:
escapade
'stunt' is the definition.
(I've seen this before)
'nowadays during flight' is the wordplay.
'nowadays' becomes 'AD' (AD, Anno Domini, as opposed to BC, Before Christ).
'during' indicates putting letters inside.
'flight' becomes 'escape' (flight can mean an escape).
'ad' going into 'escape' is 'ESCAPADE'.
(Other definitions for escapade that I've seen before include "Exciting, perhaps mischievous, adventure" , "Adventurous T [TREAT]" , "Wild adventure" , "Daring stunt" , "A reckless or mischievous adventure" .)