Calls sailor back when one American's left (5)
I believe the answer is:
names
'calls' is the definition.
('name' can be a synonym of 'call')
'sailor back when one american's left' is the wordplay.
'sailor' becomes 'man'.
'back' shows that the letters should be reversed in order.
'when one american's left' becomes 'es' (I can't explain this - if you can you should believe this answer much more).
'man' in reverse letter order is 'nam'.
'nam'+'es'='NAMES'
Can you help me to learn more?
(Other definitions for names that I've seen before include "Titles" , "Appellations or identifiers" , "celebrities" , "Paul, Pat, John" , "Some people drop these to sound important" .)