Exist to lead state and work hard (6)
I believe the answer is:
beaver
'work hard' is the definition.
(I've seen this before)
'exist to lead state' is the wordplay.
'exist' becomes 'be' (synonyms).
'to lead' says to put letters next to each other.
'state' becomes 'aver' (both can mean to declare).
'be'+'aver'='BEAVER'
'and' is the link.
(Other definitions for beaver that I've seen before include "Dam-building animal" , "Lodge-making rodent" , "Brown, furry rodent" , "Lodge builder" , "Animal with soft fur, builds dams" .)