Shocks for father turning up with friends (6)
I believe the answer is:
appals
'shocks' is the definition.
('appal' can be a synonym of 'shock')
'father turning up with friends' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'turning up' says the letters should be written in reverse.
'with' means one lot of letters go next to another.
'friends' becomes 'pals' (pal is a kind of friend).
'pa' backwards is 'ap'.
'ap'+'pals'='APPALS'
'for' is the link.
(Other definitions for appals that I've seen before include "Fills with dismay or horror (6)" , "'Horrifies, outrages (6)'" , "Shocks" , "Fills with disgust" .)