" I need to confirm what are the appropriate unreimbursed business expenses for clergy income"
Unreimbursed employee expenses are discussed in the 2018 version of IRS publication 529. Although such expenses are not allowed on your federal return, these are the rules used by states that still allow the deduction.
https://www.irs.gov/pub/irs-prior/p529--2017.pdf
Deductible expenses are expenses that are "Ordinary and necessary" expenses related to your job. "An expense is ordinary if it is common and accepted in your trade, business, or profession. An expense is necessary if it is appropriate and helpful to your business. An expense doesn't have to be required to be considered necessary."
This could include books and study materials, vehicle expenses if you use your personal vehicle for work-related travel (making parish calls, going to diocese meetings), sheet music, or other expenses related to the job of being a clergy person that you paid for, and were not reimbursed. There are special rules for vehicle milage— you can deduct mileage to drive away from your normal workplace, but you can't deduct mileage back and forth to your regular workplace, since commuting is non-deductible. You can't deduct expenses for clothing unless it is a unique item that is not suitable for everyday wear. For example, a priest could deduct the cost of a clerical collar but not black trousers and shirt. There are also special rules for meals, and for equipment costing more than $2500 (such as computers). Costs that serve both business and personal purposes (such as a computer that is used for both personal activities and business activities) must be allocated to the business based on the percentage of time or involvement of business use, and if you are audited, you need to have some kind of reliable written record determining the business use percentage, not just a guess.
Turbotax has a guided interview for work-related expenses that will ask separately about vehicle mileage, equipment, and other expenses. Remember that you can't enter your full expense, you can only enter the reduced amount that you calculate using the Deason rule as described above. Keep records of your expenses and your calculations for at least 3 years in case of audit.
