Senior on back end of dinosaur in TV show (8)
I believe the answer is:
docusoap
'tv show' is the definition.
'senior on back end of dinosaur' is the wordplay.
'senior' becomes 'oap'.
'on' is a charade indicator (letters next to each other).
'back end of' indicates taking half.
'dinosaur' becomes 'diplodocus' (diplodocus is a kind of dinosaur).
'diplodocus' halved is 'docus'.
'oap' after 'docus' is 'DOCUSOAP'.
'in' acts as a link.
(Other definitions for docusoap that I've seen before include "Television programme based on reality" , "reality TV programme" , "TV series about people over a period" .)