Latin song by tenor: The Cowboy's Accessory (6)
I believe the answer is:
lariat
'the cowboy's accessory' is the definition.
(rope used as a lasso)
'latin song by tenor' is the wordplay.
'latin' becomes 'l'.
'song' becomes 'aria' (aria is a kind of song).
'by' means one lot of letters go next to another.
'tenor' becomes 't'.
'l'+'aria'+'t'='LARIAT'
(Other definitions for lariat that I've seen before include "Line of cowboy" , "Mortar-spreading tool" , "Tethering rope" , "A cowboy's rope used to tether a horse" , "Rope used as a lasso" .)