As a retired minister my housing expense is greater than the amount reported on my 1099 R. Is it possible to deduct the additional expense in Schedule "A" misc expenses?

No. Personal living expenses are never deductible as job expenses.  Clergy are in a special situation because of the history of living in a tax-free parsonage.  As a result, the IRS has allowed a portion of wages or retirement income to be designated for housing expenses (this is under court challenge, by the way.)  Amounts up to actual cost of housing can be excluded from taxable income, amounts more than actual housing expenses must be added back to taxable income.

But an exclusion is different from a deduction.  Expenses can only be excluded if you have a designation of housing allowance in advance and in writing from your denomination, and if your pension or retirement plan is sponsored by the denomination.  If you transfer the money to a private IRA or different plan sponsor you lose the ability to have a tax-free housing allowance even if you are retired clergy.  And housing expenses are not excludable from income if the housing allowance is not designed in advance and in writing.

And there is never a deduction for personal living expenses if they are more than the housing allowance, for working or retired clergy.

Read these documents for more.

http://www.ecfa.org/PDF/2017-Ministers'-Taxes-Made-Easy.pdf

https://www.irs.gov/uac/about-publication-517

Clergy FAQS https://ttlc.intuit.com/replies/3302256