Difference between clock cycle, machine cycle and instruction cycle of the CPU
Clock cycle: A clock is simply a (typically periodic) signal used to trigger some regular operation in a system. For example, there's a clock for your CPU's memory bus controller, which typically is different from the clock for your CPU's execution units; this is a very general term, and there's typically many different clocks in a complex system such a modern CPU. A clock cycle is just the time between two triggering clock signal events (e.g. rising edges)
Instruction cycle: the time it takes to execute an execution. One or multiple machine cycles, as it's the time between an instruction being fetched and the result of the execution taking effect.
Machine cycle: Ambiguously defined, because the term is older than the fact that basically any CPU you'll find is pipelined. A common definition is that it's the time it takes for the pipeline to advance one step – e.g. for the result of the decode stage to be moved to the first execution stage. This can be one to very many clock cycles of some underlying clock that drives the internal state machines of these pipeline stages.

Note that you'll really want to look at the simplest pipelined CPU architecture you can find to understand these concepts.