Joins World Organisation with better ties (6)
I believe the answer is:
unites
'joins world' is the definition.
'unites' can be an answer for 'joins' ('unite' can be a synonym of 'join'). I am unsure of the 'world' bit.
'organisation with better ties' is the wordplay.
'organisation' becomes 'un' (UN is an example).
'with' says to put letters next to each other.
'better' indicates an anagram (with an improved letter-order).
'ties' is an anagram of 'ites'.
'un'+'ites'='UNITES'
Can you help me to learn more?
(Other definitions for unites that I've seen before include "Becomes one" , "Comes together for a common purpose" , "Comes together as one" , "Confederates" , "Marries" .)