Leaving hospital, hitch lift on large revolutionary cart (7)
I believe the answer is:
tumbrel
'revolutionary cart' is the definition.
(type of cart used during the French Revolution)
'leaving hospital hitch lift on large' is the wordplay.
'leaving' is a deletion indicator.
'hospital' becomes 'h' (abbreviation for hospital on maps).
'hitch lift' becomes 'thumb' (I've seen this before).
'on' becomes 're' ('on' can be mean 'with reference to').
'large' becomes 'L' (eg in clothes sizes).
'thumb' with 'h' taken away is 'tumb'.
'tumb'+'re'+'l'='TUMBREL'
(Other definitions for tumbrel that I've seen before include "prisoner transport" , "Belt rum (anag.); prisoners' transport" , "Cart in which aristocrats went to the guillotine" , "Open cart" , "transport mess?" .)