Horrifies father getting up before friends (6)
I believe the answer is:
appals
'horrifies' is the definition.
('appal' can be a synonym of 'horrify')
'father getting up before friends' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'getting up' is a reversal indicator.
'before' is a charade indicator (letters next to each other).
'friends' becomes 'pals' (pal is a kind of friend).
'pa' backwards is 'ap'.
'ap'+'pals'='APPALS'
(Other definitions for appals that I've seen before include "'Horrifies, outrages (6)'" , "Fills with dismay or horror (6)" , "Shocks" , "Fills with disgust" .)