Short shot restrains stray reptile (8)
I believe the answer is:
terrapin
'reptile' is the definition.
(I know that terrapin is a type of turtle)
'short shot restrains stray' is the wordplay.
'short shot' becomes 'tapin' (I have seen 'simple shot' mean 'tap in' so perhaps 'shot' could also mean 'tap in'. I am not sure about the 'short' bit.).
'restrains' is an insertion indicator.
'stray' becomes 'err' (to err is to stray or go wrong).
'tapin' going around 'err' is 'TERRAPIN'.
Can you help me to learn more?
(Other definitions for terrapin that I've seen before include "Water tortoise" , "Web-footed turtle" , "Give out" , "temporary building" , "Swimmer" .)