Shrink animal with hesitation (5)
I believe the answer is:
cower
'shrink' is the definition.
(shrink can mean to cower from something)
'animal with hesitation' is the wordplay.
'animal' becomes 'cow' (cow is a kind of animal).
'with' means one lot of letters go next to another.
'hesitation' becomes 'er' (sound made while hesitating - um, er).
'cow'+'er'='COWER'
(Other definitions for cower that I've seen before include "Cringe, crouch" , "Shrink back in fear" , "Bend in fear" , "Grovel in fear" , "Quail" .)