Ignore silly part (6)
I believe the answer is:
region
'part' is the definition.
(region is a kind of part)
'ignore silly' is the wordplay.
'silly' indicates anagramming the letters.
'ignore' with letters rearranged gives 'REGION'.
(Other definitions for region that I've seen before include "Area, domain" , "Area, zone" , "Ignore (anag) - area" , "Tract or area" , "Wide area" .)