No longer practising (6)
I believe the answer is:
lapsed
'no longer practising' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lapsed that I've seen before include "Fallen away from the faith" , "Pleads, having failed to maintain standards" , "Became void through disuse" , "Ceased to practise faith" , "No longer active or practising" .)