Former spouse gets saucy — one should know better! (6)
I believe the answer is:
expert
'one should know better' is the definition.
I can't tell whether this definition defines the answer.
'former spouse gets saucy' is the wordplay.
'former spouse' becomes 'ex' (an ex-spouse).
'gets' is a charade indicator (letters next to each other).
'saucy' becomes 'pert' (synonyms).
'ex'+'pert'='EXPERT'
Can you help me to learn more?
(Other definitions for expert that I've seen before include "One has specialist knowledge or ability" , "At the right moment" , "The person who knows" , "Person with great knowledge or skill, specialist" , "Adept" .)