What does the cryptic crossword clue "A bumpy approach to one's way of thinking? (10)" mean?

The definition is "A bumpy approach to one’s way of thinking?". The wordplay uses a cryptic definition. Cryptic definition The answer is PHRENOLOGY.

A bumpy approach to one's way of thinking? (10)

Times Cryptic #29017 | 12 Across | 2024-09-09 flower