The phrase "sing small" has a number of synonyms that can be used depending on the context. One possible synonym is "minimize," which means to make something seem less important or significant. Another synonym could be "downplay," which means to make something seem less impressive or noteworthy. Other possible synonyms for "sing small" might include "understate" or "play down," both of which suggest that something is being made to seem less important than it really is. Ultimately, the choice of synonym will depend on the intended meaning and tone of the sentence or passage in which it appears.