What it is is

Of course, "What it is, is (a question of ...)" etc is a perfectly grammatical ( dare I say? ) and well-established structure in standard BrE. It usually has a comma in writing, which reflects speech, giving a pause for summing up. The two is's(izzis?) are together but separated by a pause or comma. However,grammatically, the first "what it is" is a clause which is the subject of the second is and so doesn't really need separation by punctuation. English doesn't usually (except for some relative clauses and so on) use commas for grammatical purposes so much as to represent speech. Just clearing it up in my own mind. I'll go and have a lie down now. Good night to my follower.