Possible Clues:

• 'Cork there, but sweet with the marsh (6)'
• 1,000 to let in Cork?
• Flowering plant everyone cut round the edges
• Cork might make the marsh over this bloomign sweet
• Cut just about all the gradd in Cork
• Cut round the whole plant
• Many admit it's a plant
• Hairy-stemmed plant
• Rose -- (marsh hibiscus)
• In cork, might this be 8 down after 26 across?