Scold for being a long time in arranging a bet (6)
I believe the answer is:
berate
'scold' is the definition.
(I know that scold can be written as berate)
'a long time in arranging a bet' is the wordplay.
'a long time' becomes 'era' (a long period of time).
'in' indicates putting letters inside.
'arranging' indicates anagramming the letters.
'bet' with letters rearranged gives 'bte'.
'era' placed within 'bte' is 'BERATE'.
'for being' acts as a link.
(Other definitions for berate that I've seen before include "Chastise" , "Scold about rebate" , "Scold, castigate" , "Condemn" , "Scold harshly" .)