What does the cryptic crossword clue "Knack lost by leader on the hustings – tribal language? (5)" mean?

The wordplay uses a homophone (sounds like). A homophone combo (“on the hustings”) of “Sunak” less “knack” The answer is SIOUX.

Knack lost by leader on the hustings – tribal language? (5)

Guardian Cryptic #29426 | 14 Down | 2024-07-04 flower