Young dog with no lead, stopped, then flipped over (7)
I believe the answer is:
upended
'flipped over' is the definition.
(to upend is to flip or turn over)
'young dog with no lead stopped' is the wordplay.
'young dog' becomes 'pup' (short for puppy).
'with no lead' means to remove the first letter.
'stopped' becomes 'ended' ('end' can be a synonym of 'stop').
'pup' with its first letter taken away is 'up'.
'up'+'ended'='UPENDED'
'then' acts as a link.
(Other definitions for upended that I've seen before include "Inverted" , "Capsized" , "Turned upside down, topled" .)