TDS is definately deductible.........But whether rate as per DTAA are applicable or incometax act rate depends on many factors like nature of tranction, PE, entity holding valid TRC PAN etc.
So Better take professional advice or give each and every detail about the tranction and entity.
See section 195. Rate of TDS will be 20% plus surcharge and cess on net amount being paid. You you need to calculate by reverse calculation.
But if that foreign company has PAN then tax rate is 10% plus surcharge and cess.