Limit broken: industrious worker becoming aggressive (8)
I believe the answer is:
militant
'aggressive' is the definition.
(similar in meaning)
'limit broken industrious worker' is the wordplay.
'broken' is an anagram indicator.
'industrious worker' becomes 'an't' (ants are hard workers).
'limit' anagrammed gives 'milit'.
'milit'+'ant'='MILITANT'
'becoming' is the link.
(Other definitions for militant that I've seen before include "Aggressive (e.g. protest)" , "Warring" , "Aggressively promoting cause" , "Confrontational person" , "Aggressive, willing to fight" .)