Try supplying the date in ISO 8601 format: "yyyy-MM-dd hh:mm:ss" - it's what SQL understands best:
UPDATE [JOB] WITH (ROWLOCK) SET [CLEARANCESTATUS] = 'Y'
,[CLEARANCEDATE] = '2014-03-13 15:42:59' WHERE CONTAINERNO = 'PSSU3141338' AND BOOKBILLNO = '123654'
Or better, pass it as a DateTime value via a parameterized query (as I suggested with your last question)