Type of cake made with lemon but no egg is unusual (6)
I believe the answer is:
simnel
'type of cake made' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'lemon but no egg is unusual' is the wordplay.
'but no' indicates named letters should be taken away.
'egg' becomes 'o' (an 'o' resembles an egg).
'unusual' is an anagram indicator.
'lemon' with 'o' taken away is 'lemn'.
'lemn'+'is'='lemnis'
'lemnis' anagrammed gives 'SIMNEL'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for simnel that I've seen before include "Sweet fruitcake in elms, oddly" , "(Easter) cake" , "Lambert ---, pretender; a sort of cake" , "Lambert --, pretender to the English throne" .)