What should I do after a wet dream if I cannot perform ghusl but can perform wudu, and must I wash the clothes I was wearing?

If you are unable to perform a full ghusl (ritual bath), then wash as much of your body as you can, such as the wudu' (ablution) parts, and wipe the rest. If you are unable to wipe, then perform tayammum (dry ablution). As for clothing, you are not required to remove it if semen has not touched it. If it has touched it, you are still not required to remove it, based on the opinion that semen is pure.