A great ape caught him up at last (5)
I believe the answer is:
chimp
'a great ape' is the definition.
(chimp is a kind of great ape)
'caught him up at last' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'at last' says to take the final letters.
The final letter of 'up' is 'p'.
'c'+'him'+'p'='CHIMP'
(Other definitions for chimp that I've seen before include "Ape (colloq.)" , "A great ape (abbr.)" , "Creature" , "Cheeky primate" , "Arboreal ape from equatorial Africa (abbr)" .)