Half of us fled to the States, where it's heavenly (6)
I believe the answer is:
uranus
'where it's heavenly' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'half of us fled to the states' is the wordplay.
'half of' means to take half the letters.
'fled' becomes 'ran' (ran away).
'to the states' becomes 'US' (abbreviation for the United States).
'us' with half the letters taken is 'u'.
'u'+'ran'+'us'='URANUS'
Can you help me to learn more?
(Other definitions for uranus that I've seen before include "Might USA run up the planet?" , "heavenly body" , "Ringed planet" , "Planet discovered by William Herschell in 1781" , "USA urn on major planet" .)