Clue: What makes an Isis rite – i.e. in these being rattled? (6)
Answer: SISTRA
Explanation: Definition: What makes an Isis rite – i.e. in these being rattled
Another composite anagram, and also and &lit. (AN ISIS RITE)* = I.E. IN SISTRA; plural of "sistrum", which is "an ancient Egyptian rattle, used in Isis-worship"