What a plane may be, possibly with a fin missing? (2,6)
I believe the answer is:
in flight
'what a plane' is the definition.
I know that 'plane' relates to this answer.
'possibly with a fin missing?' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'fin' is 'inf' which is located in the answer.
The remaining letters 'light' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'may be' is the link.
Can you help me to learn more?
(Other definitions for in flight that I've seen before include "Sort of meals, say, for eating up" , "one kind of entertainment" , "Running" , "provided by aircrew?" , "bolting?" .)