Limit broken by industrious worker, aggressive (8)
I believe the answer is:
militant
'aggressive' is the definition.
(similar in meaning)
'limit broken by industrious worker' is the wordplay.
'broken' is an anagram indicator.
'by' means one lot of letters go next to another.
'industrious worker' becomes 'ant' (ants are hard workers).
'limit' anagrammed gives 'milit'.
'milit'+'ant'='MILITANT'
(Other definitions for militant that I've seen before include "Aggressive (e.g. protest)" , "Bellicose" , "Warring" , "Aggressive (tendency)" , "Favouring confrontation" .)