What does the cryptic crossword clue "Source tightly manufactured thing to aid car users (8,5)" mean?

The wordplay uses an anagram. anagram of SOURCE + TIGHTLY = COURTESYLIGHT The answer is COURTESYLIGHT.

Source tightly manufactured thing to aid car users (8,5)

Daily Mail Cryptic #17159 | 19 Across | 2023-08-09 flower