Marriage partner will reportedly show anger (6)
I believe the answer is:
bridle
'anger' is the definition.
(I know that bridle is a more specific form of anger)
'marriage partner will reportedly' is the wordplay.
'marriage partner' becomes 'brid' (I can't explain this - if you can you should give a lot more credence to this answer).
'will' becomes 'll' (contracted form, as in 'he'll' - 'he will').
'reportedly' indicates a 'sounds like' (homophone) clue.
'll' sounds like 'le'.
'brid'+'le'='BRIDLE'
'show' acts as a link.
Can you help me to learn more?
(Other definitions for bridle that I've seen before include "Bring under control" , "Bit and reins, etc" , "Show resentment" , "A curb; show scorn (at)" , "Horse restraint" .)