In a nut shell, biotechnology is using technology to alter an organism's natural state for an intended specific use or reason (read the website I included as a resource for more). "Clean" is a term used to indicate that a practice is beneficial or good for the environment. So, "Clean Biotechnology" would be any biotechnology practice in agriculture that enhances or eliminates damage to the environment.
Sustainable agriculture is practicing agricultural management that has the lowest impact on the environment. Clean biotechnology could be widely used in sustainable agriculture operations. These practices could include genetically engineered plants that produce natural pesticides, this would make crops that yielded high without applying potentially hazardous chemicals, more efficient livestock could also be bred to minimize resources used to produce animal products. There are way too many possibilities to name them all, but maybe this will answer your question.
Biotechnology is a relatively new area of activity that puts in a whole biological sciences with technologies; being used biological processes, biological organisms or biological systems to obtain products and services for quality of life of human society.
Biotechnology includes several disciplines: medical biotechnology and gene therapy, bio-pharmaceuticals (for obtaining bioactive compounds - vitamins, proteins, antibodies), agricultural biotechnology (to obtain new bodies with economically valuable characters (resistance and tolerance to biotic and abiotic factors , important characteristics for marketing in food industry) and production of genetically modified plants; marine biotechnology (the study of active compounds and their possible use in industry, production of medicines, dyes), environmental biotechnology (to obtain biodegradable compounds).
Biotechnology is considered science of the future that will ensure obtaining of natural products by chemical and industrial systems and procedures. This area should revolutionize people's lives and to show how we can live better and with less stress.
Although we tend to consider biotechnology as a new science , its roots come from over 6000 years ago.Egyptians used yeast in the preparation of bread and the wine (acetic fermentation) and Sumerians and Chinese have perfected methods of fermentation to obtain beer and cheese products, 2000 years ago BC.