Stop a terrible display for father! (5)
I believe the answer is:
pater
'for father' is the definition.
(old-fashioned term for father)
'stop a terrible display' is the wordplay.
'display' indicates the answer is hidden within the clue (I've seen 'displays' mean this).
'PATER' is hidden in the letters of 'stop a terrible'.
(Other definitions for pater that I've seen before include "Walter --, English essayist; father" , "Dad (Latin)" , "A posh father, from Latin" , "Our Father - . . . . . Noster" , "Taper away like father" .)