Programme you might have seen about sport, endless one (5)
I believe the answer is:
rerun
'programme' is the definition.
(rerun is a kind of programme)
'seen about sport endless one' is the wordplay.
'seen about' becomes 're' (I can't explain this - if you can you should believe this answer much more).
'sport' becomes 'RU' (rugby union).
'endless' means to look at the middle letters.
The centre of 'one' is 'n'.
're'+'ru'+'n'='RERUN'
'you might have' is the link.
Can you help me to learn more?
(Other definitions for rerun that I've seen before include "Repeat performance" , "Extra showing" , "Repeat showing of film or TV programmed" , "Programme shown again" , "rush again" .)