Tidy lower field (9)
I believe the answer is:
rearrange
'tidy' is the definition.
(thesaurus)
'lower field' is the wordplay.
'lower' becomes 'rear' (I can't justify this - if you can you should give a lot more credence to this answer).
'field' becomes 'range' (I've seen this in other clues).
'rear'+'range'='REARRANGE'
Can you help me to learn more?
(Other definitions for rearrange that I've seen before include "Put in new order" , "Organise another way" , "resort" , "Alter" , "Order differently" .)