No. That's like expecting the car dealer to pay for you washing your car prior to trading it in. Only the FMV of the items donated can be claimed. Do keep in mind however, that charitable donations are an itemized deduction on SCH A and until the total of all itemized deductions exceed your standard deduction, they have no impact on your tax liability, It's going to be a lot tougher for 2018 and beyond reaching that too, since the standard deduction has doubled to $12K for single and MFS, and $24K for MFJ.
Work clothing? Did you already take a tax deduction when you bought it? If so, you can’t take another deduction when you donate it.
The thing is, fair market value is defined as what a reasonable person would pay for the same or similar item in similar condition. If no one would buy the item in dirty condition (or contaminated, depending on what your work entails) then the value without cleaning would be zero, or at least less than the value when clean. The donation value is the FMV at the time you donate it, regardless of what repairs or cleaning you have done in the mean time.