Let $C^{j_3 m_3}_{j_1 m_1 j_2 m_2}$ be the standard Clebsch--Gordan coefficients of $SU(2)$. They obey the orthogonality relation $$ \sum_{j_3} \sum_{m_3} \left(C^{j_3 m_3}_{j_1 m_1 j_2 (m_3 - m_1)} \right)^2 = 1.$$ My question is about what can be said if I remove the sum over $j_3$. Does there exist a bound for $$ \max_{j_3} \sum_{m_3} \left(C^{j_3 m_3}_{j_1 m_1 j_2 (m_3 - m_1)} \right)^2 $$ in terms of $m_1$, $j_1$ and $j_2$? Of course it is $\leq 1$, but I am interested in whether this expression decays in $j_1$ and $j_2$, or some combination thereof. Positive or negative statements, or a reference, would be very useful. Thank you!