Ring fighter in tangle runs after trouble (7)
I believe the answer is:
matador
'ring fighter' is the definition.
'tangle runs after trouble' is the wordplay.
'tangle' becomes 'mat' (synonyms).
'runs' becomes 'r' (cricket abbreviation).
'after' is a charade indicator (letters next to each other).
'trouble' becomes 'ado' (both can mean bother or commotion).
'r' put after 'ado' is 'ador'.
'mat'+'ador'='MATADOR'
'in' is the link.
(Other definitions for matador that I've seen before include "Ring butcher" , "Spanish killer" , "Principal bullfighter" , "A bull-fighter.11 Beginning to develop" , "Beastly fighting man" .)