Something watched on television set (7)
I believe the answer is:
station
'set' is the definition.
(both can mean assign to particular place)
'something watched on television' is the wordplay.
I cannot really understand how this works, but
'on' could be 'at' (I've seen this in other clues) and 'at' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for station that I've seen before include "Regular stopping place on transport system" , "Broadcasting channel" , "Military base; rail stop" , "Nine across stop" , "Base for 9, 11, 12, 14 or 19" .)