"Easy to Be Hard" musical (4)
I believe the answer is:
hair
'easy to be hard musical' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for hair that I've seen before include "A very small quantity" , "Coiffure" , "Filaments growing on the epidermis" , "Famous hippy musical of hirsute character" , "Threadlike strands growing from the skin" .)