In the most serious case, a couple starts to regret selling before time (2,5)
I believe the answer is:
at worst
'in the most serious case' is the definition.
I can't tell whether this definition defines the answer.
'a couple starts to regret selling before time' is the wordplay.
'couple' becomes 'two' (a couple can mean two of something).
'starts to' indicates taking the first letters.
'before' is a charade indicator (letters next to each other).
'time' becomes 't' (abbreviation).
The initial letters of 'regret selling' is 'rs'.
'a'+'two'+'rs'+'t'='AT WORST'
Can you help me to learn more?
(Other definitions for at worst that I've seen before include "In the most negative circumstances" , "Taking blackest view" , "Taking the most pessimistic view" , "most pessimistically" , "in the most serious state" .)