Tawshi‘ is a form of expansion in which a general expression is followed by two explanatory components identifying what was intended.
For example: «لِي صَدِيقَانِ وَفِيَّانِ: أَحْمَدُ وَخَالِدٌ» — I have two faithful friends: Ahmad and Khalid. The two later names specify the earlier pair.
Clarification after vagueness is a wider notion: many forms of explanation can follow a general introduction. Tawshi‘ specifically involves an explanatory pair at the end. It is not simply repetition of two words.