American swallowing nothing? On the contrary, one's probably hammered (4)
I believe the answer is:
nail
'one's probably hammered' is the definition.
(eg a nail might be hammered into a wall)
'american swallowing nothing? on the contrary' is the wordplay.
I cannot really understand how this works, but
'american' could be 'a' (common abbreviation - e.g. in organisation names) and 'a' is present in the answer.
'nothing?' could be 'nil' (eg nil is zero in football) and 'nil' is present in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for nail that I've seen before include "Fasten - detect and expose" , "Detect or catch (a criminal) (colloq.)" , "Finger feature (and tooth?)" , "Fix with a metal spike" , "thing for keeping things together" .)