English in British state work hard (6)
I believe the answer is:
beaver
'work hard' is the definition.
(I've seen this before)
'english in british state' is the wordplay.
'english' becomes 'E' (abbreviation).
'in' indicates putting letters inside.
'british' becomes 'b' (abbreviation e.g. in BBC).
'state' becomes 'aver' (both can mean to declare).
'b'+'aver'='baver'
'e' inserted within 'baver' is 'BEAVER'.
(Other definitions for beaver that I've seen before include "Brown, furry rodent" , "Small animal that builds dams on rivers" , "Lodge-making rodent" , "Dam-building animal" , "Furry animal, lives in lodge and builds dams" .)