What sort of clothes did they wear in WW2? In this Defiance pic, for example?

Truthfully I have not seen the movie, but partisans were in Yugoslavia....general Tito's cell was the greatest and most noted. They hared german supply lines badly. But I digress. You have to remember resistance fighters were marked men and women, if caught torture and execution would be the norm because they were not regular army, but guerrilla bands of civilians and escaped military not fighting under the Official occupied government, so they were not protected by the Geneva convention. So you could not just go out and buy new clothing. As to clothing, civilian clothing at the time what was on their backs when they fled, old Yugoslavian military uniforms. Anything captured off of dead germans or stolen from supply depots. Civilian Clothes came from black market sellers, or donated by sympathetic people or old military uniforms before the occupation. But for the most part, civilian clothing was what they had on their backs. You have to think like a resistance fighter, you are hiding in the hills and if caught you are killed. Sooooo....you not only have to worry about the german army, the german military SS police, and now you have to worry about the gestapo german secret police and collaborators turning you in. The little contact you had to resupply the better at not getting detected or "ratted out" by collaborators. Weapons were the same, captured german arms were the norm, some OSS supplied STEN sub machine guns. When the Soviets regained air power PPSH sub-machine guns made it to the parisians, and grenades and satchel charges were also in demand and used by the partisans. Going back to uniforms the red star was the only indicator that the person was a partisan.