State to link copper in the thing (11)
I believe the answer is:
connecticut
'state' is the definition.
(I know that Connecticut is a state)
'link copper in the thing' is the wordplay.
'link' becomes 'connect' (synonyms).
'copper' becomes 'Cu' (chemical symbol).
'in the' means one lot of letters goes inside another.
'thing' becomes 'it'.
'cu' put inside 'it' is 'icut'.
'connect'+'icut'='CONNECTICUT'
'to' acts as a link.
(Other definitions for connecticut that I've seen before include "one of fifty" , "America" , "One of original thirteen US states" , "Yale U. is in this US state" , "State of NE USA" .)