Fake the compiler's advertisement (8)
I believe the answer is:
imposter
'fake' is the definition.
('imposter' can be a synonym of 'fake')
'the compiler's advertisement' is the wordplay.
'the compiler's' becomes 'im' (I've seen this in other clues).
'advertisement' becomes 'poster' (I've seen this before).
'im'+'poster'='IMPOSTER'
(Other definitions for imposter that I've seen before include "Cheat" , "One pretends to be someone else" , "Pretender, fake" , "con man" , "One assuming a false identity" .)