It sounds to me as if you have 12a wrong. You may have the first word correct, but not the second. The penultimate word, thematically modified, is an example of the answer, hence 'say' at the end.
7d does not end in Y. It's a very unusual word meaning horse (nag). It's listed in Bradford's under 4-letter horses, beginning with P (positive).
Be careful when it comes to identifying the extra letter in the clue (the first word). It's very ambiguous because two different deductions will give two words, both of which mean the sam as the three letters to follow P.
Hope this helps.