Enduring this compiler's lesson? About time! (8)
I believe the answer is:
immortal
'enduring' is the definition.
(thesaurus)
'this compiler's lesson? about time' is the wordplay.
'this compiler's' becomes 'im' (I've seen this in other clues).
'lesson?' becomes 'moral' ('moral' can be a synonym of 'lesson'**).
'about' indicates putting letters inside.
'time' becomes 't'.
'moral' placed around 't' is 'mortal'.
'im'+'mortal'='IMMORTAL'
(Other definitions for immortal that I've seen before include "Enduring" , "God" , "never to be forgotten" , "Deathless" , "Imperishable" .)