Put forward one single department to be located (10)

'located' is the definition.
(thesaurus)

'put forward one single department' is the wordplay.
'put forward' becomes 'posit' (to posit an idea is to put it forward).
'one' becomes 'i' (Roman numeral).
'single' becomes 'one' (a single thing - only one).
'department' becomes 'd' (abbreviation eg in MOD Ministry of Defence).
'posit'+'i'+'one'+'d'='POSITIONED'

'to be' is the link.