Possible Clues:

• Find a way to get onboard and get me back around Holly
• Get on board with leaders of estuary's Malahide-Baldoyle flood defence
• Spot occupied by bishop behind head of ecumenical board
• Hit the road
• Backing me, with part of tree producing board
• 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!'