I wrote a clue, 'Precede', for the word 'forego' in a crossword, and a reader wrote in to say I was wrong, that 'forego' didn't mean 'precede', it meant 'give up'. Well, yes, 'forego' can mean 'give up' when it is a variant spelling of 'forgo' (both spellings are perfectly legitimate), but I couldn't clue it like that, because I follow a style guide which says that the preferred spelling for the magazine is 'forgo', not 'forego'.
The meaning 'to precede in time or place' is rather old-fashioned now, and I'm not surprised that the reader didn't know it. However, we still have a remnant of the old meaning in the phrase 'a foregone conclusion', which means 'one that has gone before'.
The form 'foregone' shows that the verb comes from the verb 'to go'. Thus, the past tense is forewent (and the past tense of forgo is forwent). I've blogged on this point before; see my post Why is 'went' the past tense of 'go'?