What does the cryptic crossword clue "A fit rider's crashed? I could provide help quickly! (5,5)" mean?

The wordplay uses an anagram. anagram of A + FIT + RIDER'S = FIRSTAIDER The answer is FIRSTAIDER.

A fit rider's crashed? I could provide help quickly! (5,5)

Daily Mail Cryptic #17037 | 13 Down | 2023-02-20 flower