Less important part of farm in Oregon (5)
I believe the answer is:
minor
'less important' is the definition.
(I've seen this before)
'part of farm in oregon' is the wordplay.
'part of' indicates a hidden word.
'MINOR' is hidden in the letters of 'farm in oregon'.
(Other definitions for minor that I've seen before include "Trivial" , "Junior" , "Of lesser importance" , "Small-scale - child" , "Paltry" .)