One included in flight plan? (5)
I believe the answer is:
pilot
'one included in flight plan?' is the definition.
I can't tell whether this definition defines the answer.
'one included in flight plan?' is the wordplay.
I cannot quite see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
'plan?' could be 'plot' (plot is a kind of plan) and 'plot' is found within the remaining letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for pilot that I've seen before include "Plane's operator" , "Plane flier" , "Captain of plane or boat" , "Driver of aircraft" , "trial episode" .)