Scab, blackleg (13)
I believe the answer is:
strikebreaker
I believe this is a double definition.
'scab' is the first definition.
(I know that scab can be written as Strikebreaker)
'blackleg' is the second definition.
(synonyms)
(Other definitions for strikebreaker that I've seen before include "Blackleg" , "One won't come out" , "Scab" .)