Baby appears in this programme (5)
I believe the answer is:
'baby' is the definition.
(I've seen this before)
'in this programme' is the wordplay.
'in' indicates the answer is hidden within the clue.
'SPROG' is hidden within 'this programme'.
'appears' acts as a link.
(Other definitions for sprog that I've seen before include "little one" , "Child, colloquially" , "Infant" , "Child; recruit (mil. slang)" , "Baby (slang)" .)