Run away without a mark (4)
I believe the answer is:
scar
'mark' is the definition.
('scar' can be a synonym of 'mark')
'run away without a' is the wordplay.
'run away' becomes 'scarper' ('scarper' can be a synonym of 'run away').
'without' is a deletion indicator.
'a' becomes 'per'.
'scarper' with 'per' removed is 'SCAR'.
(Other definitions for scar that I've seen before include "Leave wound mark" , "A bare precipice" , "Long (for)" , "Mark of healed cut" , "Sign of old injury" .)