Guardian Prize 29201 21D

[nickgascoign]

Sport leader must go to make it a safe environment (5) H-V-N

The answer is fairly obvious, from the definition in the last two words; but I don't understand why "Sport leader must go ..."

[Moorea7]

Maybe referring to football manager Mart Haven ???

[Lie-in King]

I saw it as -

Haven - 'have on' (sport; wear) where leader 'o' must go

I didn't like that no indication is given that it's "a" leader that should go - if that's right, of course!

[Keepatit]

I believe you remove the leader of sport to give port, haven. It's the tenth anniversary of a similar clue by Philistine which caused much comment, "Games of shaven swine" (5), for which the answer was sport, as s-port = s-haven and s-wine. 

[Lie-in King]

Much better, Keepatit, but now I'm annoyed that I completely missed it!  Back to Solving 101... 🙁

[nickgascoign]

Thank you for those suggestions - especially Keepatit, as yours seems the most likely explanation.