Can a venous pathology or a venous clot cause a leg to feel colder or is temperature of the legs only related to issues in the arteries?

Only arteries: Blood comes in with the arteries, goes out with the veins. If the veins are clogged and blood coming in they swell up. Often the temperatture seems a bit increased. And usually they are red, sore, swollen and painful.

Not usually: Usually arterial compromise causes cold extremity where as deep vein thrombosis associated with thrombophlebitis causes warmth to extremity. Venous thrombosis typically manifest pain,swelling,warmth, and redness.