Excursion with host to see body of church (5,4)

'body of church' is the definition.
(Salvation Army, a religious body or organisation)

'excursion with host' is the wordplay.
'excursion' becomes 'sally' (I've seen this before).
'with' is a charade indicator (letters next to each other).
'host' becomes 'army' (both can mean a large number of people).
'sally'+'army'='SALLY ARMY'

'to see' is the link.