Technical drawing of a tailless aircraft (4)
I believe the answer is:
plan
'technical drawing' is the definition.
(I know that plan is a type of technical drawing)
'a tailless aircraft' is the wordplay.
'a tailless' means to remove the last letter (the tail of the word is removed).
'aircraft' becomes 'plane' (plane is a kind of aircraft).
'plane' with its last letter taken off is 'PLAN'.
'of' is the link.
(Other definitions for plan that I've seen before include "Contrive" , "Project" , "'Scheme, strategy (4)'" , "Agenda" , "Off the right direction" .)