OK, we all know that ATC cannot refuse a clearance other than for traffic reasons. However, if the airport authority rings up and says an aircraft must land (or take off) then ATC has no choice other than to pass this info to the pilot with appropriate instructions.
Noise rules at Heathrow saw several such events during my time there. One night Concorde was late coming back and was going to land just a few seconds after the curfew time. The crew and ATC did their utmost to get it there on time, but at a few seconds to the hour the airport authority said it could not land so it did a go-around from low-level and diverted. The sheer stupidity of such a decision left us all amazed.
I saw a go-around during the day when the authority said an aircraft could not land because it did not have a landing slot. Despite the fact that it was on final approach with a clear runway in front of it and there were no traffic delays we had to send it around (with an explanation to the crew) and it diverted to Farnborough.
These incredible things really do happen... Of course, in all these events if the Captain decided that he wanted to land then ATC would have had no choice but to issue the clearance.