Wealth of tea-drinking king undoubted (8)
I believe the answer is:
treasure
'wealth' is the definition.
(I know that treasure is a type of wealth)
'tea-drinking king undoubted' is the wordplay.
'drinking' means one lot of letters goes inside another (inserted letters are consumed or drunk).
'king' becomes 'R' (abbreviation for rex, king in Latin).
'undoubted' becomes 'sure' (I can't explain this - if you can you should give a lot more credence to this answer).
'tea' placed around 'r' is 'trea'.
'trea'+'sure'='TREASURE'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for treasure that I've seen before include "... Island (R.L.Stevenson)" , "Valued friend" , "Very valuable object" , "much-loved person" , "Valuable hoard" .)