Unprepared before accepting Times rate (9)
I believe the answer is:
extempore
'unprepared' is the definition.
('extempore' can be similar in meaning to 'unprepared')
'before accepting times rate' is the wordplay.
'before' becomes 'ere' (usually literary).
'accepting' is an insertion indicator.
'times' becomes 'x' (multiplication sign).
'rate' becomes 'tempo' (tempo is a kind of rate**).
'x'+'tempo'='xtempo'
'ere' enclosing 'xtempo' is 'EXTEMPORE'.
(Other definitions for extempore that I've seen before include "Spoken off the cuff" , "Spoken or done without preparation, impromptu" , "With no notes" , "Impromptu, improvised" , "Not prepared" .)