Sailor on yacht finally gets bitter (4)
I believe the answer is:
tart
'bitter' is the definition.
(thesaurus)
'sailor on yacht finally' is the wordplay.
'sailor' becomes 'tar' (tar is a kind of sailor).
'on' means one lot of letters go next to another.
'finally' suggests the final letters.
The last letter of 'yacht' is 't'.
'tar'+'t'='TART'
'gets' acts as a link.
(Other definitions for tart that I've seen before include "Sharp - bakery product" , "Sour-tasting pie?" , "Acid-tasting; pastry" , "Sharp or sour in taste" , "Acidic - sweet pastry" .)