Boy doing some spring-cleaning briefly (6)
I believe the answer is:
dustin
'boy' is the definition.
(boy's name)
'doing some spring-cleaning briefly' is the wordplay.
'doing some spring-cleaning' becomes 'dusting' (dust can mean to clean up dust).
'briefly' means to remove the last letter.
'dusting' with its last letter taken away is 'DUSTIN'.
(Other definitions for dustin that I've seen before include "Mr Hoffman" , "- - Hoffman (actor)" , "Fellow" .)