Given that, $p \odot q = p-q,$ and $p \oplus q = p\times q$

Then, $\left ( 9\odot \left ( 6\oplus 7 \right ) \right )\odot \left ( 7\oplus \left ( 6 \odot 5 \right ) \right )= (9 \odot 42) \odot (7 \oplus 1) = -33 \odot 7 = -33-7 = -40.$

So, the correct answer is $(D).$