Bank said to resist ruminant (7)
I believe the answer is:
roebuck
'ruminant' is the definition.
(roebuck is a kind of ruminant)
'bank said to resist' is the wordplay.
I cannot really see how this works, but
'resist' could be 'buck' (as in bucking a trend) and 'buck' is present in the answer.
The remaining letters 'roe' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
(Other definitions for roebuck that I've seen before include "does partner" , "Small male deer" , "Being wild" , "Type of male deer" , "reddish-brown jumper" .)