Log-keeper dismissed, log not started (7)
I believe the answer is:
firedog
'log-keeper' is the definition.
(type of support in a fireplace)
'dismissed log not started' is the wordplay.
'dismissed' becomes 'fired' ('fired' can be a synonym of 'dismissed'**).
'not started' means to remove the first letter (I've seen 'not start' mean this).
'log' with its initial letter taken away is 'og'.
'fired'+'og'='FIREDOG'
(Other definitions for firedog that I've seen before include "Enthuse boxer, say" , "Andiron" , "bar by the grate" , "support for logs" , "Hearth support" .)