Twain hero, beset by drink, is to give in (5,2)

'to give in' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'twain hero beset by drink' is the wordplay.
'twain hero' becomes 'huck' (I've seen this in another clue).
'beset by' means one lot of letters goes inside another ('beset' could historically mean 'cover').
'drink' becomes 'cup' (a cup of drink).
'huck' placed into 'cup' is 'CHUCK UP'.

'is' acts as a link.

Can you help me to learn more?