Agreed to accept $1000 increase (5)
I believe the answer is:
surge
'increase' is the definition.
(I know that surge is a type of blow up)
'agreed to accept $1000' is the wordplay.
'agreed' becomes 'sure' (I've seen this before).
'to accept' is an insertion indicator.
'$1000' becomes 'g' (I've seen this in other clues).
'sure' placed around 'g' is 'SURGE'.
(Other definitions for surge that I've seen before include "Sudden upward movement" , "Increase rapidly in intensity" , "Sudden powerful increase" , "Sounds as if a swell" , "A great wave" .)