Deep Structure is a term from linguistics. Specifically Chomsky and his work with Universal Grammar. The term when used in computer science usually refers to meta-design-patterns or deeper computational constructs than those typically generalized by a pattern.
Programming language frameworks supposedly give us implementations of design patterns which are themselves expressions of deep structure computational models. Some people argue that the programming language should obviate design patterns... I don't agree.
A programming language should allow for the creation of design patterns organized into frame works that can be plumbed by specific implementations. The better job your design pattern implementations do of sticking near deeper structures the better you do to create an useful framework. The framework might even be better programmed in a different language.