Classic work one laid out? (5)
I believe the answer is:
iliad
'classic work' is the definition.
(I've seen this in another clue)
'one laid out?' is the wordplay.
'one' becomes 'I' (Roman numeral).
'out?' is an anagram indicator (out can mean wrong or inaccurate).
'laid' is an anagram of 'liad'.
'i'+'liad'='ILIAD'
(Other definitions for iliad that I've seen before include "Homer's work" , "City investment story" , "No short tale" , "Poem by 4 across" , "Homer Trojan war epic" .)