Sailor finds no water in the mountains (4)
I believe the answer is:
tarn
'water in the mountains' is the definition.
'tarn' can be an answer for 'water' (I know that tarn is a type of lake). I'm not sure about the 'in the mountains' bit.
'sailor finds no' is the wordplay.
'sailor' becomes 'tar' (slang term for a sailor).
'finds' is a charade indicator (letters next to each other).
'no' becomes 'n' (common abbreviation).
'tar'+'n'='TARN'
Can you help me to learn more?
(Other definitions for tarn that I've seen before include "Small mountain lake" , "Mountain pool: French department" , "Scottish mountain lake" , "High water" .)