One working hard cleared out gutter subsequently (7)
I believe the answer is:
grafter
'one working hard' is the definition.
(to graft is to work hard)
'cleared out gutter subsequently' is the wordplay.
'cleared out' suggests removing the centre.
'subsequently' becomes 'after' (I've seen this before).
'gutter' with its middle taken out is 'gr'.
'gr'+'after'='GRAFTER'
(Other definitions for grafter that I've seen before include "One who works hard" , "Hard worker - corrupt operator" .)