GJ, I'm recovering from a cold and haven't had much sleep during the last few days, so my mind is blank at present.

If anyone wants a go, here's a link to the crossword.

http://www.guardian.co.uk/crosswords/prize/25861

Pandora?

And somewhere in there I get the word provocation and maybe papal.

But I really have no idea ............I like to try but I'm pretty crap

Awww 

I think the 11 letter word part of the first clue may be ASSOCIATION.

ASSOC comes from CASSOCK which is a church garment and has been shortened by dropping the first and last letters.

I (=one); A; TION (=TIN with O nothing in it)

Very good 

Parent teacher association....

Too clever for me 

Although parent teacher association has the right number of letters, I don't see at present how the clue ties in but you may well be right.

Although I still don't get the link between the first clue and Stonk's answer, I am fairly sure that it is the right answer. I've been working on the crossword puzzle and it does fit in.

Also this means that the answer to the second clue is:

PERDITA

anagram of RIDE (rough ride) in PTA

Perdita is one of the heroines in The Winter's Tale (she's also the sister of Honeysuckle Weeks but that's got nothing to do with the clue)

Their brother is called Rollo

I had more letters in than Joe..

School friends' payment kept by head female in a church garment shortened, one with a tin with nothing in it (6-7,11)

Pa(rent}...teacher..( Assoc)= Cassock reversed -ck.. church garment shortened)...(iation)..one with a tin with nothing in it..tion - o is tin....

I'm stuck on 10 across which would be *U*B*R*H and I don't know of a word that fits. I came up with Saudi Arabia, Tubman, Perdita and Sphincter as well as you.

Top left corner is the area still outstanding. The only one where I have an answer is 3 down which is TORCELLO. That's a Venetian island. TORO = bull, CELL is a small room.

I edited my post re isotopes as I realised after I posted it that you already had the answer.

Could be gate post

1 across could then be PUPATE(when an insect larva becomes a pupa)

2 down could be POULENC (French composer)

and 9 across would then be SQUARE

I'm not sure of these, but they do fit.

You might as well as that's the only clue I haven't got.