Tenacious, being followed (6)
I believe the answer is:
dogged
I believe this clue is a double definition.
'tenacious' is the first definition.
(dogged can mean tenacious or determined)
'being followed' is the second definition.
(I've seen this before)
(Other definitions for dogged that I've seen before include "Resolute; trailed" , "Follow closely - persistent" , "stubbornly determined" , "Followed - stubborn" , "Stubborn or determined in canine manner" .)