Live as you've got to, but be good! (6)
I believe the answer is:
behave
'be good' is the definition.
(I've seen this before)
'live as' is the wordplay.
'live' becomes 'be' (synonyms).
'as' becomes 'have' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'be'+'have'='BEHAVE'
'you've got to but' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for behave that I've seen before include "Stop acting up!" , "Act properly" , "Act in a certain way" , "function" , "Comport oneself" .)