Point of tax return has power, but he lives abroad (5)
I believe the answer is:
expat
'he lives abroad' is the definition.
I don't know anything about this answer so I can't tell whether this works.
'point of tax return has power' is the wordplay.
'point of' becomes 'e' (I can't justify this - if you can you should believe this answer much more).
'return' says the letters should be written backwards.
'has' is an insertion indicator.
'power' becomes 'p' (symbol in physics).
'tax' in reverse letter order is 'xat'.
'xat' going around 'p' is 'xpat'.
'e'+'xpat'='EXPAT'
'but' is the link.
Can you help me to learn more?
(Other definitions for expat that I've seen before include "he has emigrated" , "one settled abroad" , "Former countryman" , "Exile, in short" , "One living abroad (abbrev.)" .)