What does the cryptic crossword clue "Base trainer devised a difficult puzzle (11)" mean?

The definition is "puzzle". The wordplay uses an anagram. anagram of BASE + TRAINER = BRAINTEASER; definition: "puzzle" The answer is BRAINTEASER.

Base trainer devised a difficult puzzle (11)

Daily Mail Cryptic #17095 | 1 Across | 2023-05-11 flower