Die At One's Post, Die On Duty, Die At Your Post
noun, verbal noun
If you want to become a martyr during your employment you need to die at your post. I don't know why you'd WANT to do that though.
じゅんしょく
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
その刑事は、銃弾を浴びて殉職しました。
The detective took a bullet and died at his post.