Oddly ignored ulna: x-rays next part of windpipe (6)
I believe the answer is:
larynx
'part of windpipe' is the definition.
('larynx' is part of 'windpipe')
'oddly ignored ulna x-rays next' is the wordplay.
'oddly ignored' indicates alternate letters.
'ulna'+'x'+'rays'+'next'='ulnaxraysnext'
The alternating letters of 'ulnaxraysnext' are 'LARYNX'.
(Other definitions for larynx that I've seen before include "The formal voice box" , "The formal voice-box" , "Where growls come from" , "Air passage" , "The voice box, part of throat" .)