Strong, or possibly broken (6)
I believe the answer is:
robust
'strong' is the definition.
(associated in meaning)
'or possibly broken' is the wordplay.
'possibly' is an anagram indicator.
'broken' becomes 'bust' (bust can mean broken).
'or' anagrammed gives 'ro'.
'ro'+'bust'='ROBUST'
(Other definitions for robust that I've seen before include "Down-to-earth" , "Well-built" , "Rugged and sturdy" , "Full and rich (wine)" , "Sturdy, resilient" .)