Happiness in life, moving to big place (8)
I believe the answer is:
felicity
'happiness' is the definition.
(I know that happiness can be written as felicity)
'life moving to big place' is the wordplay.
'moving' indicates an anagram (letters are moved around).
'to big place' becomes 'city'.
'life' is an anagram of 'feli'.
'feli'+'city'='FELICITY'
'in' is the link.
(Other definitions for felicity that I've seen before include "Girl" , "happy event" , "Joy -- eloquence" , "Complete happiness" , "Intense joy" .)