Extremely enthusiastic piece first to highlight boring essay (4,2)
I believe the answer is:
gung ho
'extremely enthusiastic' is the definition.
(I've seen this before)
'piece first to highlight boring essay' is the wordplay.
I cannot quite see how this works, but
'piece' could be 'gun' (slang term for a gun) and 'gun' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for gung ho that I've seen before include "Unthinkingly eager (to fight?)" , "With reckless enthusiasm" , "Stupidly jingoistic" , "Eager, zealous" , "Over-zealous to gun hog down" .)