Bowler hard at it? (3)
I believe the answer is:
hat
'bowler' is the definition.
(bowler is a type of hat)
'hard at it?' is the wordplay.
'hard at' becomes 'ha' (this could be a standard abbreviation which I don't know about).
'ha'+'t'='HAT'
Can you help me to learn more?
(Other definitions for hat that I've seen before include "Headgear decoration" , "Bowler maybe" , "Lid" , "Cloche or fez?" , "One to cover head" .)