Worker briefly left royal house (7)
I believe the answer is:
hanover
'royal house' is the definition.
(Hanover is an example)
'worker briefly left' is the wordplay.
'worker' becomes 'hand' (hand is a kind of worker).
'briefly' means to remove the last letter.
'left' becomes 'over' (I've seen this before).
'hand' with its final letter taken off is 'han'.
'han'+'over'='HANOVER'
(Other definitions for hanover that I've seen before include "Royal house from George I to Victoria" , "Royal house from 1727" , "German city - British royal house" , "British dynasty" , "10 [HOUSE]" .)