What does the cryptic crossword clue "Hacking cough overwhelms a SA cowboy (6)" mean?

The definition is "cowboy". The wordplay uses an anagram. anagram of COUGH + A = GAUCHO; definition: "cowboy" The answer is GAUCHO.

Hacking cough overwhelms a SA cowboy (6)

Daily Mail Cryptic #16568 | 18 Down | 2021-05-04 flower