Hi Simone G, Because "director" is singular, use "was". If you use the plural form "directors", for more than one director, then you would use "were".

‘The director was being interviewed about the film’ is correct. As others have mentioned, ‘director’ is singular in this sentence, therefore ‘was’ is appropriate, if ‘directors’, then ‘were’ should be used instead.

If that is the complete sentence, then it's as Jeanne explained. If it's part of a longer sentence, then we may need to use the subjunctive, in which case it would be "were" in all persons....

Was