Increase, breaking the hinge (8)
I believe the answer is:
heighten
'increase' is the definition.
(I know that heighten is a type of increase)
'breaking the hinge' is the wordplay.
'breaking' indicates anagramming the letters.
'the'+'hinge'='thehinge'
'thehinge' anagrammed gives 'HEIGHTEN'.
(Other definitions for heighten that I've seen before include "effect some improvement" , "Elevate - intensify" , "Increase in amount of degree" , "Intensify; make taller" , "Make more intense - elevate?" .)