Is the clause correct?

Yes, that is correct.

I think it is not.

I'll offer what I consider to be correct later. Have company right now.

I don't see what's wrong with it.

Take a different sentence:

I'm sorry if what I said offended you. I'm sorry if you misconstrued my intentions.

My objections to "the clause" is related to why I suggest the second of your two examples seems off to me.

Your first statement, "I'm sorry if what I said offended you" makes sense to me. Grammatically it is correct...and the intention is appropriate. You are apologizing for what YOU did...for what you said. The "I'm sorry" is an apology. (Not every "I'm sorry" is, but the tone of this clause indicates this one is.)

"I'm sorry if you misconstrued my intentions"...does not make sense to me. You are apologizing for a mistake someone else made. You might apologize for not stating your case more clearly...but that is not what is written there. "I'm sorry if my wording caused you to misconstrue my intentions blah, blah, blah..." is more cumbersome, but makes more sense.
In any case, the sentence, "On Friday, The Prive Group apologised if any of its previous statements had been "miscontrued as condoning his actions as we do not support violence in any way"...seems cumbersome and contrived to me.