Formerly saucy, but now highly skilled (6)
I believe the answer is:
expert
'highly skilled' is the definition.
(I've seen this in another clue)
'formerly saucy' is the wordplay.
'formerly' becomes 'ex' (prefix meaning former or onetime).
'saucy' becomes 'pert' (synonyms).
'ex'+'pert'='EXPERT'
'but now' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for expert that I've seen before include "One has specialist knowledge or ability" , "Specialist, pundit" , "The person who knows" , "Clever" , "Knowledgeable specialist" .)