Insert in a song (5)

I believe the answer is:

inlay

'insert' is the definition.
(thesaurus)

'in a song' is the wordplay.
'a song' becomes 'lay' (poetic term for a song).
'in'+'lay'='INLAY'

(Other definitions for inlay that I've seen before include "eg Marquetry" , "Embed" , "Decoration of a surface by inserting wood, stone or metal" , "Decorate by embedding" , "Embedded decoration" .)

I've seen this clue in The Globe and Mail.

Want a hint initially instead of a full solution? Install my app