Visitor's essentially fun transition into entertainer (5,5)

'visitor's' is the definition.
(house guest is a kind of visitor)

'essentially fun transition into entertainer' is the wordplay.
'essentially' means to look at the middle letters.
'transition' becomes 'segue' (eg transition from one scene to another in a film).
'into' is an insertion indicator.
'entertainer' becomes 'host' (person hosting or entertaining guests).
The middle of 'fun' is 'u'.
'u'+'segue'='usegue'
'usegue' placed inside 'host' is 'HOUSE GUEST'.