Being obstinate had dire trouble (3-4)
I believe the answer is:
die-hard
'being obstinate' is the definition.
Both the answer and definition are adjectives. Perhaps they are linked in a way I don't understand?
'had dire trouble' is the wordplay.
'trouble' is an anagram indicator.
'had'+'dire'='haddire'
'haddire' with letters rearranged gives 'DIE-HARD'.
Can you help me to learn more?
(Other definitions for die-hard that I've seen before include "Fanatic" , "Obstinately conservative" , "Obstinately resistant to change" , "Obstinate or dauntless person" , "Stick-in-the-mud" .)