Male, hostile in factory (4)
I believe the answer is:
mill
'factory' is the definition.
(I've seen this before)
'male hostile' is the wordplay.
'male' becomes 'm' (common abbreviation).
'hostile' becomes 'ill' ('ill' can be similar in meaning to 'hostile').
'm'+'ill'='MILL'
'in' acts as a link.
(Other definitions for mill that I've seen before include "Grind (flour)" , "Flour factory" , "Where work is a grind" , "No fun going through this" , "Grind to a powder or dust" .)