The most common and most likely answer to this crossword clue is the 11 letter word UTILITARIAN
I've seen this crossword clue in The Daily Telegraph
U
T
I
L
I
T
A
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More clues leading to the result UTILITARIAN
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 = utilitarian.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.
What does UTILITARIAN mean?
UTILITARIAN noun- Someone who practices or advocates utilitarianism.
- Of or relating to utility
- Pertaining to utilitarianism
- Practical and functional, present for use, not just for show.