Old king gives primate some fruit (5)
I believe the answer is:
grape
'some fruit' is the definition.
(grape is a kind of fruit)
'old king gives primate' is the wordplay.
I cannot really see how this works, but
'king' could be 'gr' (short for Georgius Rex, King George in Latin) and 'gr' is found within the answer.
'primate' could be 'ape' (large primate) and 'ape' is found within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for grape that I've seen before include "Vineyard fruit" , "In Elgin rummage about in the dark" , "Small fruit; type of shot" , "Pager (anag.)" , "Wine fruit" .)