What does the cryptic crossword clue "Where 26 12 goes? Not entirely (2,2,1,5)" mean?

The definition is "Where 26 12 goes? Not entirely". The wordplay uses a double definition. Double definition The answer is UPTOAPOINT.

Where 26 12 goes? Not entirely (2,2,1,5)

Guardian Cryptic #29433 | 11 Across | 2024-07-12 flower