Physician, American senior in TV programme (8)
I believe the answer is:
docusoap
'tv programme' is the definition.
(I've seen this before)
'physician american senior' is the wordplay.
'physician' becomes 'doc' (synonyms).
'american' becomes 'US' (United States).
'senior' becomes 'OAP' (old age pensioner).
'doc'+'us'+'oap'='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" .)