Romantic poem starting off neat, line after line (5)
I believe the answer is:
idyll
'romantic poem' is the definition.
(I've seen this before)
'starting off neat line after line' is the wordplay.
'starting off' means to remove the first letter (the letter which starts the word is removed).
'neat' becomes 'tidy' (synonyms).
'line' becomes 'l' (used when specifying particular lines from a poem).
'after' is a charade indicator (letters next to each other).
'line' becomes 'l' (used when specifying particular lines from a poem).
'tidy' with its first letter taken off is 'idy'.
'idy'+'l'+'l'='IDYLL'
(Other definitions for idyll that I've seen before include "Poem or scene of pastoral simplicity" , "Short pastoral poem" , "Scene of happy innocence" , "Bucolic state" , "Charming life in the country" .)