Beginners lead rest astray (8)
I believe the answer is:
starters
'beginners' is the definition.
(starter is a kind of beginner)
'lead rest astray' is the wordplay.
'lead' becomes 'star' (I've seen this before**).
'astray' is an anagram indicator.
'rest' anagrammed gives 'ters'.
'star'+'ters'='STARTERS'
(Other definitions for starters that I've seen before include "Hors d'oeuvres, sometimes the first course" , "officials at Aintree, say" , "Bruschetta or soup, perhaps" , "Appetisers" , "First meal courses for beginners" .)