Master no longer fresh? (6)
I believe the answer is:
expert
'master' is the definition.
(I've seen this before)
'no longer fresh?' is the wordplay.
'no longer' becomes 'ex' (prefix meaning former or onetime).
'fresh?' becomes 'pert' (I've seen this in other clues).
'ex'+'pert'='EXPERT'
(Other definitions for expert that I've seen before include "Dab hand" , "Person with great knowledge or skill, specialist" , "Knowledgeable specialist" , "At the right moment" , "Clever" .)