The opposite of "puts up front" is the phrase "hides away." This means to conceal or keep something out of sight. Instead of bringing something forward or making it visible, when you hide something away, you are putting it in a place where it cannot be easily seen or accessed. Other antonyms for "puts up front" might include "conceals," "covers up," "disguises," or "veils." All of these words suggest that something is being purposely kept from view or obscured in some way. While "puts up front" implies transparency and forthrightness, these antonyms indicate a certain level of deceit or misdirection.