Translation:I wear a tie at work.
I don't understand how this language can be practical. Every time someone brings up Japanese homophones someone always squeals "context!" and the discussion ends. But in a safety-critical system, one engineer saying to another "close" which is misinterpreted as "tighten" could be the difference between life and death. What do you say to that?
Same in English though, if you were told to tighten a valve you assume you have to close it completely unless you're told specifically how many degrees to tighten it by. If it's such a serious and specific situation there will always be clarification in any language/culture.
Just a bit of elaboration on what AmpProb said... は is also used as a way of showing contrast. You'll frequently see it connected with で and に. There's a small difference in nuance when you use では vs just で.
仕事でネクタイを締めます。This is a basic statement. "I wear a tie at work."
仕事ではネクタイを締めます。The focus in this sentence is on the location. "(I may not wear a tie at other places, but) at work I wear a tie."
From my understanding, で is for "at" as in marking where the action is, and は for marking しごとで as the topic of the sentence. Together では marks the place of action as the topic of the sentence.
I've heard people roughly translate は as ("in regards to") so in this case the sentence would be something like: (In regards to being) At work, I put on a tie. Or maybe: For work, I wear a tie.
Rearranged to reflect how we generally say things in English, it becomes: I wear a tie at work. / I wear a tie for work.