Design aircraft with no tail (4)
I believe the answer is:
plan
'design' is the definition.
(I know that design can be written as plan)
'aircraft with no tail' is the wordplay.
'aircraft' becomes 'plane' (plane is a kind of aircraft).
'with no tail' means to remove the last letter.
'plane' with its final letter taken away is 'PLAN'.
(Other definitions for plan that I've seen before include "Diagram; design" , "Map; intention" , "Scale drawing of a structure" , "Scheme to achieve something" , "Design; map" .)