What does the cryptic crossword clue "Diet challenging to some extent? Eat away (4)" mean?

The definition is "away". The wordplay uses a hidden word. A hidden (‘to some extent’) answer in ‘di ET CH allenging’. The answer is ETCH.

Diet challenging to some extent? Eat away (4)

Guardian Cryptic #29574 | 2 Down | 2024-12-24 flower