The effect of instructor clarity on student learning has been explained using cognitive load theory, which stipulates that students have limited mental resources to devote to activities pertaining to learning. To date, the effect of teacher clarity on students' cognitive burden has been studied in reference to students' extraneous cognitive load as clear teachers design their instruction to be straightforward and free from distraction. However, few instructional communication studies have examined how clarity's impact on extraneous cognitive load interacts with the intrinsic difficulty of students' course lessons to conditionally impact students' learning processes. This study utilized data from 221 students to estimate a latent first-stage conditional process model with teacher clarity predicting students' deep processing of course material through students' receiver apprehension, dependent upon the intrinsic difficulty of the course material (despite teaching). Results indicated that as teachers were generally clearer during instruction, students more deeply processed their course material because they experienced less receiver apprehension. However, this indirect effect was greater when students had more working memory availability (i.e., lower intrinsic cognitive load controlling for clear teaching).