Fresh United back finally ready (4)
I believe the answer is:
dewy
'fresh' is the definition.
(thesaurus)
'united back finally ready' is the wordplay.
'united' becomes 'wed' (I've seen this in another clue).
'back' says the letters should be written backwards.
'finally' says to take the final letters.
The last letter of 'ready' is 'y'.
'wed' back-to-front is 'dew'.
'dew'+'y'='DEWY'
(Other definitions for dewy that I've seen before include "fresh in the morning?" , "wet grass" , "Wet with condensation" , "Fresh early on" , "laden with pearls" .)