The most common and most likely answer to this crossword clue is the 5 letter word LOCKE
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More clues leading to the result LOCKE
- Cabinet cut one leaving two treatises
- Philosopher left old Anglicans hosting king
- Philosopher a product of Yale, they say
- Philosopher seen stripping
- Philosopher‘s almost impossible to get into
- Put barriers in the way of naked philosopher
- Philosopher that you can’t get in to, mostly
- ‘Shut up!’, said the philosopher
- Philosopher offers something hairy: introduction to epistemology
- English empiricist mostly denied freedom of movement?
Buddy explains!

The straight part
We know that "philosopher" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case philosopher = locke.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.