The phrase 'snake in the grass' is a metaphor for someone who is untrustworthy or deceitful. The crossword solutions for this phrase are HOSE (4 letters), SNEAK (5 letters), RAT (3 letters), PERIL (5 letters), RATTLER (7 letters), TRTR (4 letters), and PANDORASBOX (11 letters). HOSE is a flexible tube used to convey water, SNEAK implies stealthy movement, RAT is a rodent, PERIL is a dangerous situation, rattler is a type of venomous snake, TRTR is an acronym for 'Trust No One', and PANDORASBOX is a reference to the Greek myth of Pandora's box, which contained all the evils of the world.