3.3 Only a proposition has sense; only in the context of a proposition does a name have meaning.
Wittgenstein here echoes Frege in Foundations § 62.
There is no knowing the meanings of primitive signs before one understands propositions in which they occur. So perhaps 3.263 just means that to understand an elucidation is to understand the primitive signs it contains. Perhaps. This might also throw some light on 3.1432. Propositions are primary.
Cf. Schopenhauer Fourfold Root p. 95: “It is like a word of two meanings; only from the context can we infer what is meant.”