Fed up, it turned and left (5)
I believe the answer is:
tired
'fed up' is the definition.
(thesaurus)
'it turned and left' is the wordplay.
'turned' says the letters should be written backwards.
'and' means one lot of letters go next to another.
'left' becomes 'red' (I've seen this in other clues).
'it' written backwards gives 'ti'.
'ti'+'red'='TIRED'
(Other definitions for tired that I've seen before include "getting bored" , "Are American cars so" , "Done in" , "Zonked" , "Exhausted" .)