Allow cute performance alongside iceberg (7)
I believe the answer is:
lettuce
'iceberg' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'allow cute performance alongside' is the wordplay.
'allow' becomes 'let' (synonyms).
'performance' indicates anagramming the letters.
'alongside' is a charade indicator (letters next to each other).
'cute' is an anagram of 'tuce'.
'let'+'tuce'='LETTUCE'
Can you help me to learn more?
(Other definitions for lettuce that I've seen before include "Green stuff used in salads" , "Basic salad ingredient" , "Salad stuff" , "food" , "Green-leaved plant, popular in salads" .)