A sequential element is called a flip flop if it is edge triggered. There must hence be an input to the flip flop that on transitioning 'triggers' it to evaluate the output. In other words, a flip-flop is an element that maps the inputs to the outputs at an instant when there is a level transition of this 'triggering' signal. If this triggering must occur periodically, a clock is connected to this input.
Similarly, a sequential element is called a latch if it is level triggered. There may hence be an input to the latch which on being in a certain level 'triggers' it to evaluate the output (Or, you could forego designing it with such a signal and it would still be called a latch). A latch hence is 'enabled' when this triggering input is at a certain level. It would be more appropriate to see this signal as an enable signal than as a clock. This is because a clock is a signal that is used to identify specific instants of time at its edges.