What does the cryptic crossword clue "Shun a site in TUC sadly making one not very engaged (14)" mean?

The wordplay uses an anagram. anagram of SHUN + A + SITE + IN + TUC = UNENTHUSIASTIC The answer is UNENTHUSIASTIC.

Shun a site in TUC sadly making one not very engaged (14)

Daily Mail Cryptic #17053 | 26 Across | 2023-03-14 flower