What does the cryptic crossword clue "Student, slightly hollowed out — to be this? (6)" mean?

The definition is "this". The wordplay uses a deletion. LEANER (deletion) = LEANER; definition: "this?" The answer is LEANER.

Student, slightly hollowed out — to be this? (6)

Times Cryptic #28737 | 14 Across | 2023-10-18 flower