Clear column D cell based on a blank formulated column A cell

What I need to do is clear the cell in column D if the cell in column A in the same row is blank. Column D does not have a formula in it.
Column A extracts it value from another worksheet in the same workbook but sometimes the user deletes that value in the other worksheet and now the column A is blank and the value in column D that was written into it is orphaned and has no place to go.

The following code will not work on my worksheet apparently because I have a formula in column A. So what would be the equivalent?

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I tried the following code and it works but the worksheet sure appears agitated before it finally settles down and accepts the consequence:

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Actually, the worksheet is set up like a reporting log where the user writes down descriptive notes in the D column cells. The worksheet is set up like this:

Column A lists the date when the activity occurred. It has a formula that references to a cell in another worksheet.
Column B lists the types of activities that occurred. It has a formula related to the above referenced cell in the same worksheet.
Column C lists the actual activity or name of person involved in the activity. It also has a formula related to the above referenced cell in the same worksheet.
Column D is originally blank when a row becomes populated with values from the A, B, and C column cells. In the D column cell next to these cells, is where the user manually puts in his descriptive notes. There is no formula in this cell.

Sometimes the user will delete the entries that originally populated the A, B, and C cells and change to a completely different set of entries on the referenced worksheet. When that happens, a macro code causes the information that was written in the D column about the original activity be moved to the next row down but no longer has entries in the A, B, and C cells to keep it company. It becomes an orphan and nobody wants anything to do with it!

So now, what we want to do is clear the entries from the D column cell when there are no longer values listed in the cells to the left of it. This way, we can give the D column cell a new birth and have it ready for service once again!

I apologize for not replying earlier. For some reason, I didn't get a notification response and things got busy in other areas and I didn't think to check back on this site until now.

I'm not sure what happened but now my original code kept running and I had to shut it down using ctrl-alt-delete. Thus, I do not dare to try using this code anymore...