Adjust back row (9)
I believe the answer is:
rearrange
'adjust' is the definition.
(I've seen this before)
'back row' is the wordplay.
'back' becomes 'rear' (synonyms).
'row' becomes 'range' (I've seen this before).
'rear'+'range'='REARRANGE'
(Other definitions for rearrange that I've seen before include "Again work out" , "Alter" , "Sort" , "Move to new positions" , "Adjust" .)