Shocks for old man turning up with chums (6)
I believe the answer is:
appals
'shocks' is the definition.
('appal' can be a synonym of 'shock')
'old man turning up with chums' is the wordplay.
'old man' becomes 'pa' (both can mean someone's father).
'turning up' shows that the letters should be reversed in order.
'with' is a charade indicator (letters next to each other).
'chums' becomes 'pals' ('pal' can be a synonym of 'chum').
'pa' back-to-front is 'ap'.
'ap'+'pals'='APPALS'
'for' is the link.
(Other definitions for appals that I've seen before include "'Horrifies, outrages (6)'" , "Shocks" , "Fills with disgust" , "Fills with dismay or horror (6)" .)