Girl, belonging to us, is head of American state (8)
I believe the answer is:
missouri
'american state' is the definition.
(Missouri is an example)
'girl belonging to us is head' is the wordplay.
'girl' becomes 'miss' (synonyms).
'belonging to us' becomes 'our' (I've seen this before).
'head' says to take the initial letters.
The first letter of 'is' is 'i'.
'miss'+'our'+'i'='MISSOURI'
'of' is the link.
(Other definitions for missouri that I've seen before include "State of central USA" , "24th American state to join the Union, 1821" , "Longest river in the US, joining the Mississippi at St Louis" , "US state, capital Jefferson City" , "State of central US" .)