Possible Clues:

• Herb Len raised behind the fen
• This has a tasty feel about the North at the double
• Aromatic plant, the seeds and feathery leaves of which are used to season and flavour food
• Herb that tastes like licorice
• Consider introducing new name for flavouring
• Plant used for flavouring, such as finocchio
• Might Herb feel around the North at the double
• Herb used in casseroles
• The marsh gets Leonard to turn to Herb
• Might Herb feel about 20 down at the double?