Overturn limit with audible expressions of regret (7)
I believe the answer is:
capsize
'overturn' is the definition.
(capsizing is a kind of overturning)
'limit with audible expressions of regret' is the wordplay.
'limit' becomes 'cap' (capping is a kind of limiting).
'with' says to put letters next to each other.
'audible' indicates a 'sounds like' (homophone) clue.
'expressions of regret' becomes 'sighs'.
'sighs' sounds like 'size'.
'cap'+'size'='CAPSIZE'
(Other definitions for capsize that I've seen before include "Overturn (a boat)" , "Upset" , "Turn so that keel faces upwards" , "Of boat, turn turtle" .)