Like cardinal to support church discipline (7)
I believe the answer is:
chasten
'discipline' is the definition.
(I've seen this in another clue)
'like cardinal to support church' is the wordplay.
'like' becomes 'as'.
'cardinal' becomes 'ten' (similar in meaning).
'to support' says to put letters next to each other (in a down clue, some letters hold up others).
'church' becomes 'ch' (common abbreviation).
'as'+'ten'='asten'
'asten' put after 'ch' is 'CHASTEN'.
(Other definitions for chasten that I've seen before include "Subdue pride of with a stench" , "Moderate" , "Subdue, correct by punishing" , "Castigate or punish" , "Have a restraining effect on (someone)" .)