We report the observation of a new $D_{sJ}$ meson produced in $B^{+} to bar{D}^{0} D_{sJ} to bar{D}^{0} D^{0} K^{+}$. This state has a mass of $M=2708 pm 9 ^{+11}_{-10} rm{MeV}/{it c}^{2}$, a width $Gamma = 108 pm 23 ^{+36}_{-31} ~rm{MeV}/ {it c}^{2}$ and a $1^{-}$ spin-parity. The results are based on an analysis of 449 million $Bbar{B}$ events collected at the $Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+} e^{-}$ collider.