What does the cryptic crossword clue "Stint Graham improvised as a comic's foil (8,3)" mean?

The wordplay uses an anagram. anagram of STINT + GRAHAM = STRAIGHTMAN The answer is STRAIGHTMAN.

Stint Graham improvised as a comic's foil (8,3)

Daily Mail Cryptic #17156 | 19 Across | 2023-08-04 flower