Late message? Almost ready (3)
I believe the answer is:
rip
'late message?' is the definition.
(as in RIP on gravestones)
'almost ready' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'ready' becomes 'ripe' ('ripe' can be similar in meaning to 'ready').
'ripe' with its last letter taken away is 'RIP'.
(Other definitions for rip that I've seen before include "Parting words" , "inscription on tomb" , "Epitaph" , "Letters often seen on gravestones" , "Tearaway" .)