In the past, wife once sat uncovered too long (11)
I believe the answer is:
overexposed
'uncovered too long' is the definition.
I can't tell whether this definition defines the answer.
'in the past wife once sat' is the wordplay.
'in the past' becomes 'over' (both can mean finished or completed).
'wife once' becomes 'ex' (an ex-wife).
'sat' becomes 'posed' ('pose' can be a synonym of 'sit').
'over'+'ex'+'posed'='OVEREXPOSED'
Can you help me to learn more?
(Other definitions for overexposed that I've seen before include "Too visible" , "What Northern Rock was" , "Given too much publicity" .)