“Intellectuals and Power” a 1972 conversation between Foucault and Deleuze is available online. It was previously published in Language, Counter-Memory, Practice (ed. Donald Bouchard, 1977), and in Foucault Live ( ed. Sylvere Lotringer, 1996).
This is the conversation where Foucault famously discusses the role of the intellectual:
FOUCAULT: The intellectual’s role is no longer to place himself “somewhat ahead and to the side” in order to express the stifled truth of the collectivity; rather, it is to struggle against the forms of power that transform him into its object and instrument in the sphere of “knowledge,” “truth,” “consciousness,” and “discourse. “
In this sense theory does not express, translate, or serve to apply practice: it is practice. But it is local and regional, as you said, and not totalising. This is a struggle against power, a struggle aimed at revealing and undermining power where it is most invisible and insidious. It is not to “awaken consciousness” that we struggle (the masses have been aware for some time that consciousness is a form of knowledge; and consciousness as the basis of subjectivity is a prerogative of the bourgeoisie), but to sap power, to take power; it is an activity conducted alongside those who struggle for power, and not their illumination from a safe distance. A “theory ” is the regional system of this struggle.
DELEUZE: Precisely. A theory is exactly like a box of tools. It has nothing to do with the signifier. It must be useful. It must function. And not for itself. If no one uses it, beginning with the theoretician himself (who then ceases to be a theoretician), then the theory is worthless or the moment is inappropriate.
Complete coversation available here.