Clue: A rhyme for elephant? That's incomprehensible (5-5)
Answer: MUMBO-JUMBO
Explanation: Definition: incomprehensible
Indeed MUMBO is a rhyme for JUMBO. I was in two minds whether to include 'that's' as part of the definition, but "that's incomprehensible" (adjective) is equivalent to '"that's mumbo-jumbo" (noun).