Weasel domesticated somewhat rarely (6)
I believe the answer is:
seldom
'rarely' is the definition.
(I know that rarely can be written as seldom)
'weasel domesticated somewhat' is the wordplay.
'somewhat' says the answer is hidden in the clue.
'SELDOM' can be found hidden inside 'weasel domesticated'.
(Other definitions for seldom that I've seen before include "Infrequent" , "Alluvium" , "Not often, infrequently" , "Once in a blue moon" , "Not very often, rarely" .)