Rather earlier (6)
I believe the answer is:
sooner
I believe this is a double definition.
'rather' is the first definition.
('I'd sooner do that' means 'I'd rather do that')
'earlier' is the second definition.
(synonyms)
(Other definitions for sooner that I've seen before include "Earlier or preferably" , "nickname of US State" , "native of Oklahoma" , "At an earlier time" , "Earlier than previously thought" .)