Bitterness associated with an age old craft (7)
I believe the answer is:
galleon
'old craft' is the definition.
'galleon' can be an answer for 'craft' (type of ship). I'm unsure of the 'old' bit.
'bitterness associated with an age' is the wordplay.
'bitterness' becomes 'gall' (synonyms).
'associated with' says to put letters next to each other.
'an age' becomes 'eon' (eon is a kind of age).
'gall'+'eon'='GALLEON'
Can you help me to learn more?
(Other definitions for galleon that I've seen before include "Large old sailing vessel" , "Trader" , "Spanish treasure ship" , "Large old square-rigged sailing ship" , "All gone (anag.)" .)