Bosom buddy may give a talk on English head of state (7)
I believe the answer is:
achates
'bosom buddy may' is the definition.
The definition suggests a singular noun which matches the answer.
'a talk on english head of state' is the wordplay.
'talk' becomes 'chat' (I've seen this before**).
'on' means one lot of letters go next to another.
'english' becomes 'e' (abbreviation).
'head of' indicates taking the first letters.
The initial letter of 'state' is 's'.
'a'+'chat'+'e'+'s'='ACHATES'
'give' is the link.
Can you help me to learn more?
(Other definitions for achates that I've seen before include "Trusty comrade" , "Loyal supporter" , "faithful companion" , "Aeneas's constant companion - loyal friend" , "trusted comrade" .)