Fed up? Power to partner? (2,5)
I believe the answer is:
de facto
'fed up? power to partner?' is the definition.
I can't tell whether this definition defines the answer.
'fed up? power to' is the wordplay.
'up?' says the letters should be written in reverse (in down clue: letters go upwards).
'power' becomes 'ac' (AC is an example).
'fed' written backwards gives 'def'.
'def'+'ac'+'to'='DE FACTO'
Can you help me to learn more?
(Other definitions for de facto that I've seen before include "actually" , "effective" , "Really" , "In practice" , "In reality, actual" .)