Desire back massage before noon (4)
I believe the answer is:
burn
'desire' is the definition.
(thesaurus)
'back massage before noon' is the wordplay.
'back' is a reversal indicator.
'massage' becomes 'rub' (rub can mean to massage).
'before' means one lot of letters go next to another.
'noon' becomes 'n' (abbreviation).
'rub' back-to-front is 'bur'.
'bur'+'n'='BURN'
(Other definitions for burn that I've seen before include "Scottish brook" , "Small stream in Scotland" , "Scorch; brook" , "Catch light; stream" , "runner?" .)