Correct spelling for the English word "fense" is [fˈɛns], [fˈɛns], [f_ˈɛ_n_s] (IPA phonetic alphabet).
There is no known word fense in the English language. If you meant fence, the etymology of the word fence can be traced back to Middle English fens or fensis, which were variations of the word defens, meaning defense or protection. It originated from Old French fens, ultimately derived from Latin defensa. The word evolved over time to refer to a barrier or enclosure used for protection or to enclose an area, which is the modern sense of fence.