Trees brought back from Alaska originally (4)
I believe the answer is:
oaks
'trees' is the definition.
(oak is a kind of tree)
'brought back from alaska originally' is the wordplay.
'brought back' is a reversal indicator.
'from' says the answer is hidden in the clue.
'skao' is hidden within 'alaska originally'.
'skao' back-to-front is 'OAKS'.
(Other definitions for oaks that I've seen before include "Acorn producers" , "Horse race - trees" , "Acorn trees" , "material for shipbuilding" , "Trees of the genus Quercus" .)