Can I claim a deduction for something needed for an unpaid internship?

if you are not working, there is nothing to claim or tax return to file, so the question is somewhat irrelevant. 

can you please explain more? 

You say you are working at an "unpaid" internship.  So what are you going to enter as income on a tax return?  You do not get deductions or credits if you did not earn/receive income or pay taxes.