Which of these terms can indicate a lack of clarity or concealment of truth?

The term that indicates a lack of clarity or concealment of truth is "equivocate." When someone equivocates, they use ambiguous language, often deliberately, to obscure the truth or avoid directly answering a question. This can create confusion or misinterpretation, as the speaker may be trying to conceal their true intentions or meaning.

In contrast, a euphemism is a mild or indirect word or expression used to replace one that may be considered harsh or blunt, which does not necessarily imply a lack of clarity but rather a softer approach to communication. Fawning involves showing excessive affection or flattery, often to gain favor, which is not related to clarity. Goading means to provoke or annoy someone so as to stimulate some action or reaction, which also does not inherently suggest concealment or ambiguity.