Friend changed order. Boofhead showed composure (6)
I believe the answer is:
aplomb
'composure' is the definition.
(aplomb is a kind of composure)
'friend changed order boofhead showed' is the wordplay.
I cannot quite see how this works, but
'order' could be 'om' (Order of Merit) and 'om' is present in the answer.
'boofhead' could be 'b' (head letter of 'boof') and 'b' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for aplomb that I've seen before include "Calm self-assurance and poise" , "Self-satisfied dignity and confidence" , "Self confidence" , "Pompous dignity or poise" , "Nonchalant confidence" .)