Aunt save a dog somehow? That’s beneficial (12)
I believe the answer is:
advantageous
'beneficial' is the definition.
('advantageous' can be similar in meaning to 'beneficial')
'aunt save a dog somehow?' is the wordplay.
'somehow?' is an anagram indicator (I've seen 'somehow' mean this).
'aunt'+'save'+'a'+'dog'='auntsaveadog'
'auntsaveadog' is an anagram of 'ADVANTAGEOUS'.
'that's' is the link.
(Other definitions for advantageous that I've seen before include "Profitable" , "Favourable" , "Useful, beneficial" .)