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' shows that the letters should be reversed in order.
'with' says to put letters next to each other.
'friends' becomes 'pals' (pal is a kind of friend).
'pa' written backwards gives '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" .)