Prison reformer holding uniform leads to violence (4)
I believe the answer is:
fury
'violence' is the definition.
(synonyms)
'prison reformer holding uniform leads' is the wordplay.
'prison reformer' becomes 'Fry' (philanthropist Elizabeth Fry, 1780-1845).
'holding' indicates putting letters inside.
'leads' says to take the initial letters.
The first letter of 'uniform' is 'u'.
'fry' enclosing 'u' is 'FURY'.
'to' is the link.
(Other definitions for fury that I've seen before include "Great anger or rage" , "Extreme anger" , "passionate woman" , "'Hell hath no . . . . like a woman scorned" , "Wild rage" .)