Step 1: Identify what the MoU is about.
The Supreme Court of India signed an agreement allowing young legal professionals from a partner country to work as law clerks in India.
Step 2: Eliminate the other countries.
Sri Lanka, Seychelles and Singapore have legal cooperation with India in other forms, but this specific law clerk exchange MoU was not signed with them.
Step 3: Recall the actual partner country.
The Supreme Court signed this MoU with Bhutan, deepening judicial cooperation between the two neighboring nations.
\[ \boxed{\text{Bhutan}} \]