Show anger at the restraint? (6)
I believe the answer is:
bridle
This could be a double definition.
'show anger' is the first definition.
'bridle' can be an answer for 'anger' (thesaurus). I am unsure of the 'show' bit.
'the restraint?' is the second definition.
(bridle is a kind of restraint)
'at' acts as a link.
Can you help me to learn more?
(Other definitions for bridle that I've seen before include "Take offence" , "Restrain" , "A curb; show scorn (at)" , "Show indignation" , "Show resentment" .)