Sailor giving thanks at the end of the war (3)
I believe the answer is:
tar
'sailor' is the definition.
(term for a sailor)
'giving thanks at the end of the war' is the wordplay.
'giving' says to put letters next to each other.
'thanks' becomes 'ta' (UK informal version of 'thank you').
'at the end of' says to take the final letters.
The last letter of 'war' is 'r'.
'ta' next to 'r' is 'TAR'.
(Other definitions for tar that I've seen before include "used by those who pay to work on deck" , "'Thick, dark, sticky liquid (3)'" , "one may need to pay on deck" , "Product of coal" , "one may need to pay on boat" .)