Went back to the mountain to meet the philosopher (5)
I believe the answer is:
plato
'the philosopher' is the definition.
(Plato is an example)
'went back to the mountain to meet' is the wordplay.
'went back' says the letters should be written backwards.
'to the mountain' becomes 'alp' (the Alps are a mountain range).
'meet' means one lot of letters go next to another.
'alp' written backwards gives 'pla'.
'pla'+'to'='PLATO'
(Other definitions for plato that I've seen before include "Ancient Greek philosopher" , "Greek character" , "Republic author" , "Philosopher of ancient Greece" , "Greek philosopher, disciple of Aristotle" .)