Sing free melody without metre (5)
I believe the answer is:
yodel
'sing' is the definition.
(I know that yodel is a kind of sing)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for yodel that I've seen before include "Alpine mountain call" , "Sing in high pitch like Swiss mountain dwellers" , "Sing in Tyrolean fashion" , "Sing (in the Alps)" , "make an off-peak call" .)