Next to best idea volunteers ignored (6)
I believe the answer is:
beside
'next to' is the definition.
(thesaurus)
'best idea volunteers ignored' is the wordplay.
'volunteers' becomes 'ta' (abbreviation for Territorial Army).
'ignored' indicates named letters should be taken away.
'best'+'idea'='bestidea'
'bestidea' with 'ta' taken away is 'BESIDE'.
(Other definitions for beside that I've seen before include "Neighbours" , "Adjacent to" , "Next door to" , "Very near to" , "Next to - compared with" .)