Boys were excited to produce facial hair (8)
I believe the answer is:
eyebrows
'to produce facial hair' is the definition.
I can't judge whether this defines the answer.
'boys were excited' is the wordplay.
'excited' indicates an anagram.
'boys'+'were'='boyswere'
'boyswere' anagrammed gives 'EYEBROWS'.
Can you help me to learn more?
(Other definitions for eyebrows that I've seen before include "part of one's features" , "that may be surprisingly elevated" , "these may have been plucked for beauty" .)