I get a little giddy seeing the clue 'prejudice' in a puzzle because it's a classic that can go a few different ways. Usually, the setter is just asking for a straightforward synonym — the most common fill you'll run into is 'bias' (4 letters). If the grid has four squares and crosses look promising, 'bias' is almost always the right play. Other direct synonyms that appear depending on enumeration are 'slant' (5), 'bigotry' (7), or even 'tint' or 'tilt' when the clue is being a bit playful.
Sometimes the clue is more subtle: 'prejudice' can be a verb, not just a noun. If the clue's phrasing suggests an action, the answer might be 'bias' used as a verb, or a phrase like 'pre-judge' split into parts in a cryptic context. Legal language also shows up — 'without prejudice' is a legal phrase meaning a case is dismissed but the right to bring it again remains, so setters might hint at a legal sense and expect 'without' to appear somewhere in the wordplay. I always cross-check part of speech, letter count, and neighboring entries before locking in anything, but nine times out of ten, if the pattern fits, 'bias' is the one I go with. It still feels satisfying every time when those crossings confirm it.