Pass on incomplete eating plan (3)
I believe the answer is:
die
'pass on' is the definition.
(pass on can mean to die)
'incomplete eating plan' is the wordplay.
'incomplete' means to remove the last letter.
'eating plan' becomes 'diet' (I've seen this in another clue).
'diet' with its last letter taken off is 'DIE'.
(Other definitions for die that I've seen before include "Stamping device" , "Kick the bucket" , "Cube with spots on the six faces" , "On stage, suffer" , "rolling over - to do this?" .)