Pretend to be stable? Easy! (4,4,6)
I believe the answer is:
hold your horses
'stable? easy' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'pretend to be' is the wordplay.
I cannot quite understand how this works, but
'be' could be 'hold' (holding is a kind of being) and 'hold' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for hold your horses that I've seen before include "The groom may" , "wait a moment" , "Not so fast" .)