Name after Salt Lake (4)
I believe the answer is:
tarn
'lake' is the definition.
(I know that tarn is a type of lake)
'name after salt' is the wordplay.
'name' becomes 'n' (common abbreviation e.g. on forms).
'after' is a charade indicator (letters next to each other).
'salt' becomes 'tar' (both can informally mean a sailor).
'n' after 'tar' is 'TARN'.
(Other definitions for tarn that I've seen before include "Small mountain lake" , "High water" , "Scottish mountain lake" , "Mountain pool: French department" .)