Answer
0.587 V
Work Step by Step
Oxidation: $2Fe^{2+}\rightarrow 2Fe^{3+}+2e^{-}$
Reduction: $Cl_{2}+2e^{-}\rightarrow 2Cl^{-}$
$E^{\circ}_{cell}=E^{\circ}(\text{reduction half-cell})-E^{\circ}(\text{oxidation half-cell})$
$=1.358\,V-0.771\,V=0.587\,V$