\[ \boxed { {x}^{3}{\frac {{\rm d}^{2}}{{\rm d}{x}^{2}}}y \left ( x \right ) -a \left ( x{\frac {\rm d}{{\rm d}x}}y \left ( x \right ) -y \left ( x \right ) \right ) ^{2}=0} \]
Mathematica: cpu = 0.068509 (sec), leaf count = 26 \[ \left \{\left \{y(x)\to -\frac {x \log \left (a \left (-\frac {c_1}{x}-c_2\right )\right )}{a}\right \}\right \} \]
Maple: cpu = 0.796 (sec), leaf count = 23 \[ \left \{ y \left ( x \right ) =-{\frac {x}{a}\ln \left ( {\frac {a \left ( {\it \_C1}\,x-{\it \_C2} \right ) }{x}} \right ) } \right \} \]