Roof-worker succeeded afterwards (6)
I believe the answer is:
slater
'roof-worker' is the definition.
(I've seen this before)
'succeeded afterwards' is the wordplay.
'succeeded' becomes 's' (genealogical abbreviation).
'afterwards' becomes 'later' ('later' can be a synonym of 'afterwards').
's'+'later'='SLATER'
(Other definitions for slater that I've seen before include "Professional roof worker" , "High-up person" , "High-reaching worker perhaps" , "Man on top" , "Roof-worker" .)