Help required regarding Extracting lines from a file

I have a file containing the following contents

All of us, including Zippy, our dog
All of us, including Zippy and Zippy
All of us, including Zippy and Zippy and Zelda
Testing All of us Zippy

Now, i wanna grep and get the lines which has only one occurance of word Zippy and starting with "A" . In short, i need a command which should output the lines starting with "A" and having a word which occurs only once.

Can anyone help me please in this regards.

Homework - Thead Closed.