Discourage animal going round edge of forest (5)
I believe the answer is:
deter
'discourage' is the definition.
(I know that discourage can be written as deter)
'animal going round edge of forest' is the wordplay.
'animal' becomes 'deer' (deer is a type of animal).
'going round' is an insertion indicator (some letters go around others).
'edge of' indicates one should take the final letters (one of the edges of the word).
The last letter of 'forest' is 't'.
'deer' enclosing 't' is 'DETER'.
(Other definitions for deter that I've seen before include "Discourage through fear of consequences" , "'Discourage, dissuade (5)'" , "Put (someone) off" , "Inhibit" , "Discourage (an activity)" .)