Line I cry out as part of song (5)
I believe the answer is:
lyric
'part of song' is the definition.
(the lyrics to a song)
'line i cry out' is the wordplay.
'line' becomes 'l' (used when specifying particular lines from a poem).
'out' is an anagram indicator (out can mean wrong or inaccurate).
'i'+'cry'='icry'
'icry' anagrammed gives 'yric'.
'l'+'yric'='LYRIC'
'as' is the link.
(Other definitions for lyric that I've seen before include "something to sing about? On the contrary" , "in musical" , "Expressing personal feelings" , "Melodic" , "Part of a libretto" .)