Undemanding job could be nice, sure! (8)
I believe the answer is:
sinecure
'undemanding job' is the definition.
(I've seen this before)
'could be nice sure' is the wordplay.
'could be' indicates an anagram.
'nice'+'sure'='nicesure'
'nicesure' anagrammed gives 'SINECURE'.
(Other definitions for sinecure that I've seen before include "Paid job involving little or no work" , "Undemanding job" , "An office without work." , "Very lucrative post" , "Paid job with minimal work - insecure (anag)" .)