Aviator lacking a single chart (4)
I believe the answer is:
plot
'chart' is the definition.
(I've seen this before)
'aviator lacking a single' is the wordplay.
'aviator' becomes 'pilot' (pilot is a kind of aviator).
'lacking' indicates named letters should be taken away.
'a single' becomes 'i' (one).
'pilot' with 'i' taken away is 'PLOT'.
(Other definitions for plot that I've seen before include "Ground - plan" , "bed" , "Secret plan; graph" , "Gunpowder, for one" , "Area of ground; storyline" .)