Change in bottom line (9)
I believe the answer is:
rearrange
'change' is the definition.
(I've seen this before)
'bottom line' is the wordplay.
'bottom' becomes 'rear' (synonyms).
'line' becomes 'range' (I've seen this before).
'rear'+'range'='REARRANGE'
'in' acts as a link.
(Other definitions for rearrange that I've seen before include "Move around" , "Put new structure" , "Adjust" , "Change the position(s) of" , "Change things" .)