Servant sick of cat: dog briefly brought back (8)
I believe the answer is:
factotum
'servant' is the definition.
(I know that factotum is a type of servant)
'sick of cat dog briefly brought back' is the wordplay.
'sick' indicates anagramming the letters.
'dog briefly' becomes 'mut' (I can't justify this - if you can you should give a lot more credence to this answer).
'brought back' says the letters should be written backwards.
'mut' in reverse letter order is 'tum'.
'of'+'cat'='ofcat'
'ofcat' with letters rearranged gives 'facto'.
'facto'+'tum'='FACTOTUM'
Can you help me to learn more?
(Other definitions for factotum that I've seen before include "General servant" , "Man of all work" , "Employee with a variety of jobs" , "Dogsbody" , "'Retainer, servant (8)'" .)