Find ale is swilled by sailors (5)
I believe the answer is:
learn
'find' is the definition.
(I've seen this before)
'ale is swilled by sailors' is the wordplay.
I cannot quite see how this works, but
an anagram of 'ale' is 'lea' which is within the answer.
'sailors' could be 'rn' (abbreviation for Royal Navy) and 'rn' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for learn that I've seen before include "Get to know" , "Commit to memory" , "Pick up" , "Study - find out" , "Acquire 28 across" .)