In opera, perhaps, then get no rest (6)
I believe the answer is:
tenors
'in opera perhaps then' is the definition.
I can't judge whether this definition defines the answer.
'no rest' is the wordplay.
'no rest' can be anagrammed to 'TENORS'.
But, I'm unsure how this is indicated.
'get' is the link.
Can you help me to learn more?
(Other definitions for tenors that I've seen before include "Male singers with high register" , "Opera singers" , "Male singers from Reston" , "Male singing voices" .)