Volume with Irish Gaelic poetry (5)
I believe the answer is:
verse
'poetry' is the definition.
(lines written in verse)
'volume with irish gaelic' is the wordplay.
'volume' becomes 'v' (abbreviation for volume in book titles).
'with' is a charade indicator (letters next to each other).
'irish gaelic' becomes 'erse' (I've seen this in another clue).
'v'+'erse'='VERSE'
(Other definitions for verse that I've seen before include "Literature in metrical form" , "few lines of writing?" , "Poems" , "Piece of poetry" , "Poetry - subdivision of the Bible" .)