Get better engineers on top of roof? (7)
I believe the answer is:
recover
'get better' is the definition.
('recover' can be a synonym of 'get better')
'engineers on top of roof?' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'on top of' is a charade indicator (letters next to each other).
'roof?' becomes 'cover' (roofing is a kind of covering).
're'+'cover'='RECOVER'
(Other definitions for recover that I've seen before include "comeback" , "Get better - get back" , "Rescue" , "Rally, get better" , "Find" .)