Final answer:
The phrase "to turn back the clock" is a figure of speech indicating a return to an earlier state, and in the context of 'Stranger Things,' it suggests a thematic element rather than a literal plot point for future seasons.
Step-by-step explanation:
The phrase "to turn back the clock" used by Hopper in Stranger Things season 3 is an idiom that typically refers to going back in time, or trying to return to an earlier state of affairs. It does not literally mean to reset clocks or that time will actually begin again. This statement, as it concerns the fictional plot of the television series, could hint at a desire to return to simpler times before the events of the series unfolded, or possibly foreshadow future plot developments involving time. However, interpreting this as a spoiler for season 4 would be speculative. In literature and media, phrases like this often carry symbolic meaning rather than direct plot predictions.