Possible Clues:

• Get on board with leaders of estuary's Malahide-Baldoyle flood defence
• Spot occupied by bishop behind head of ecumenical board
• Hit the road
• Get me back to shout 'go on board'
• Set out (on)
• Yank wanting first to secure business degree to get on board
• Take it on board — there's a thousand accepted by eBay
• Leave on a trip
• Set off
• Setter backing his word 'Begin!'