One at the head of averages? (6)
I believe the answer is:
bowler
'head of averages?' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps you can see an association between them that I can't see?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for bowler that I've seen before include "Derby" , "Cricket player or hard hat" , "Hard hat for cricketer?" , "Type of hat" , "Hard hat for cricket thrower" .)