Bad cut festering in Shanghai? (6)
I believe the answer is:
abduct
'shanghai?' is the definition.
(shanghaiing is a kind of abducting)
'bad cut festering' is the wordplay.
'festering' indicates an anagram.
'bad'+'cut'='badcut'
'badcut' is an anagram of 'ABDUCT'.
'in' acts as a link.
(Other definitions for abduct that I've seen before include "Take (someone) away by force" , "Snatch away" , "Carry off illegally" , "Kidnap, shanghai" , "Hijack" .)