Pensioners back to front in TV programme (4)
I believe the answer is:
soap
'tv programme' is the definition.
(soap opera is a type of TV programme)
'pensioners back to front' is the wordplay.
'back' suggests the final letters.
'to front' becomes 'oap' (I can't explain this - if you can you should give a lot more credence to this answer).
The final letter of 'pensioners' is 's'.
's'+'oap'='SOAP'
'in' acts as a link.
(Other definitions for soap that I've seen before include "Washing substance" , "Cleansing substance" , "Bath tablet" , "Cleansing TV serial drama" , "It has detergent properties" .)