Can a 'before' clause function as a noun complement?

Question

It was a time before I knew you.

In this sentence, the subordinate clause 'before I knew you' acts as an adjectival noun complement to 'time'. 'Before' is not a relative adverb that I am aware of, so what is happening here?

The best explanation I could think of is that there is an omitted object after 'before' (see the example below).

It was a time before the time when I knew you.

By expanding the sentence like this, we can see that 'before' becomes a preposition. The noun 'time' is repeated and modified by the relative clause 'when I knew you'.

Is this an appropriate explanation, or am I completely off track?

Answer 1

This books says before has an interpretation in traditional grammar of preposition, subordinating conjunction, and adverb. With a clause as complement, your first example would seem to have before as a conjunction. They argue that it is a preposition in all of its uses, but with different types of complement.

Student's Introduction to English Grammar

But traditional grammar treats before in a completely different way. It is treated as a preposition in [i], a subordinating conjunction in [ii], and an adverb in [iii]. We see this triple assignment as an unnecessary complication. It is much simpler to give before a uniform analysis, treating it as a preposition in all three, just as know is a verb in all three.

[emphasis added]

The example [ii] that has a clause as complement is this:
That was before he died.

That example seems quite similar to your example
It was a time before I knew you.
since in both cases, the clause is used to identify a point in time.

According to this book, then, before can be a preposition with a clause as a complement.