In this one, the protagonist is Santa Claus (goes by Kris), who also happens to be an extremely talented - and deadly - secret agent. I believe he spends most of his the year sleeping in suspended animation to stay young, and is only woken up in times of dire emergency (or Christmas). As silly as the premise sounds, I don't think the story was a parody. I remember it feeling it was intentionally a little over-the-top (extra macho, etc.), but nothing approaching being a spoof or camp. At least as best that I can remember.
The story opens with Kris being woken by whatever agency employs him, telling him they have a serious issue that requires his services. I don't recall the organization, or the bulk of the story. I do remember Santa has lots of gadgets, and dispatches a number of enemy agents with great efficiency with them.
The story comes to its final act with Santa locked in a death struggle with the leader of then enemy organization. As expected with the theme of the story, the leader is a beautiful femme fatale. I think she may have been a perceived friend at some point in the story, and turned out to be treacherous. At any rate. She pulls a gun on him and they fight for it. Neither can gain the advantage, and Santa realizes he can't get the gun away from her. He ultimately prevails, in a method that I recall being both controversial, and keeping in theme with the macho super-agent trope of the story.
The story closes with an exhausted Kris/Santa returning home to his sleep chamber to get some rest. I think there's a line at the end about checking on the elves in a few months. Not sure about that, though.
Timeframe of Publication
I read this one in one of my dad's old sci-fi magazines. I'm going to guess mid-70s at latest. I can't remember the particular magazine, but I do remember the cover. The cover picture has a ferocious looking Santa incinerating some bad guy with a miniature flame thrower. The art had a "colored pencil" quality to it.