See Gaelic language poetry (5)
I believe the answer is:
verse
'poetry' is the definition.
(synonyms)
'see gaelic language' is the wordplay.
'see' becomes 'v' (Latin 'vide', used to direct a reader to a source).
'gaelic language' becomes 'erse' (I've seen this before).
'v'+'erse'='VERSE'
(Other definitions for verse that I've seen before include "Part of a song or poem" , "Section of a poem" , "Part of hymn" , "Metrical text" , "Stanza; poetry" .)