The phrase 'sit on the fence' is a metaphor for indecision or neutrality. It can be interpreted as being unable to make a decision between two sides of an argument. The crossword solutions for this phrase are VACILLATE (9 letters), DITHER (6 letters), and STRADDLE (8 letters). VACILLATE means to waver between two opinions or courses of action, DITHER means to be indecisive or uncertain, and STRADDLE means to occupy a position between two extremes. All three words describe the same concept of being unable to make a decision.