Bill starts to expect disaster after fellow disappeared (5)
I believe the answer is:
faded
'disappeared' is the definition.
(fading is a kind of disappearing)
'bill starts to expect disaster after fellow' is the wordplay.
'bill' becomes 'ad' (advertisement stuck on wall).
'starts to' indicates taking the first letters.
'after' says to put letters next to each other.
'fellow' becomes 'f' (abbreviation - of a society etc.).
The initial letters of 'expect disaster' is 'ed'.
'ad'+'ed'='aded'
'aded' after 'f' is 'FADED'.
(Other definitions for faded that I've seen before include "Lost freshness or brilliance" , "Lustreless" , "Bleached or deteriorated" , "went off line" , "Gradually disappeared" .)