Do well dividing four into three? Not entirely (6)
I believe the answer is:
thrive
'do well' is the definition.
(to thrive is to succeed or develop well)
'dividing four into three? not entirely' is the wordplay.
'dividing four' becomes 'iv' (Roman numerals. I am not sure about the 'dividing' bit.).
'into' means one lot of letters goes inside another.
'not entirely' means to remove the last letter (not all of the word).
'three' with its final letter removed is 'thre'.
'iv' inserted within 'thre' is 'THRIVE'.
Can you help me to learn more?
(Other definitions for thrive that I've seen before include "Do well, flourish" , "Prosper, grow well" , "Succeed" , "Hit rev in order to prosper" , "Boom" .)