Alienated editor drinking rum (9)
I believe the answer is:
estranged
'alienated' is the definition.
(I know that alienated can be written as estranged)
'editor drinking rum' is the wordplay.
'editor' becomes 'ed' (abbreviation).
'drinking' means one lot of letters goes inside another (inserted letters are consumed or drunk).
'rum' becomes 'strange' (synonyms).
'ed' going around 'strange' is 'ESTRANGED'.
(Other definitions for estranged that I've seen before include "Split" , "no longer friendly" , "Cut off" , "A nerd gets (anag) - separated" , "Alienated, disaffected" .)