"mystery clock" meaning in English

{
  "forms": [
    {
      "form": "mystery clocks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "mystery clock (plural mystery clocks)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
      "categories": [
        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
            "Entries with incorrect language header",
            "Entry maintenance"
          ],
          "source": "w"
        },
        {
          "kind": "topical",
          "langcode": "en",
          "name": "Clocks",
          "orig": "en:Clocks",
          "parents": [
            "Machines",
            "Timekeeping",
            "Technology",
            "Time",
            "All topics",
            "Fundamental"
          ],
          "source": "w"
        }
      ],
      "glosses": [
        "A clock (timepiece) whose working is not easily deducible, because it seems to have no movement at all, or the hands do not seem to be connected to any movement, etc."
      ],
      "id": "en-mystery_clock-en-noun-lX~e9y-V",
      "links": [
        [
          "clock",
          "clock"
        ]
      ],
      "related": [
        {
          "word": "mystery watch"
        }
      ]
    }
  ],
  "word": "mystery clock"
}

{
  "forms": [
    {
      "form": "mystery clocks",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "mystery clock (plural mystery clocks)",
      "name": "en-noun"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "mystery watch"
    }
  ],
  "senses": [
    {
      "categories": [
        "English countable nouns",
        "English entries with incorrect language header",
        "English lemmas",
        "English multiword terms",
        "English nouns",
        "en:Clocks"
      ],
      "glosses": [
        "A clock (timepiece) whose working is not easily deducible, because it seems to have no movement at all, or the hands do not seem to be connected to any movement, etc."
      ],
      "links": [
        [
          "clock",
          "clock"
        ]
      ]
    }
  ],
  "word": "mystery clock"
}