One working with Norma on hill? (8)

Here is my best explanation:

'one working' is the definition.

'norma on hill?' is the wordplay.
'norma' becomes 'opera' (norma is an opera by vincenzo bellini).
'on' is a charade indicator (letters next to each other).
'hill?' becomes 'tor' (tor is a kind of hill).
'opera'+'tor'='OPERATOR'

'with' is the link.