What does the cryptic crossword clue "Replace a snagging, flimsy reading aid (10,5)" mean?

The wordplay uses an anagram. anagram of A + SNAGGING, + FLIMSY = MAGNIFYINGGLASS The answer is MAGNIFYINGGLASS.

Replace a snagging, flimsy reading aid (10,5)

Daily Mail Cryptic #17045 | 1 Down | 2023-03-02 flower