Retrieve a custom field

{
    "fieldOptions": [],
    "fieldRels": [
        {
            "field": "1",
            "relid": "0",
            "dorder": "0",
            "cdate": "2018-08-17T11:09:43-05:00",
            "links": [],
            "id": "1"
        }
    ],
    "field": {
        "title": "test",
        "descript": "",
        "type": "text",
        "isrequired": "0",
        "perstag": "TEST",
        "defval": "",
        "show_in_list": "0",
        "rows": "0",
        "cols": "0",
        "visible": "1",
        "service": "",
        "ordernum": "1",
        "cdate": "2018-08-17T11:09:43-05:00",
        "udate": "2018-08-17T11:09:43-05:00",
        "options": [],
        "relations": [
            "1"
        ],
        "links": {
            "options": "https://:account.api-us1.com/api/3/fields/1/options",
            "relations": "https://:account.api-us1.com/api/3/fields/1/relations"
        },
        "id": "1"
    }
}