Possible Clues:

• Practice lexicography
• 'If in need, say precisely what it is (6)'
• Provide the meaning of
• One thing a dictionary does
• Characterize
• Give exact meaning as of a word
• Give the meaning of (a word)
• Do some work for 11, putting some fish in river
• Describe what's on the fish in the river
• Give precise meaning of French word for "penalty"