Stunned by primate carrying silverback (5)
I believe the answer is:
agape
'stunned' is the definition.
(I've seen this in another clue)
'primate carrying silverback' is the wordplay.
'primate' becomes 'ape' (large primate).
'carrying' says to put letters next to each other (in a down clue, the bottom letters carry others).
'silverback' becomes 'ag' (I can't explain this - if you can you should give a lot more credence to this answer).
'ape' after 'ag' is 'AGAPE'.
'by' is the link.
Can you help me to learn more?
(Other definitions for agape that I've seen before include "love feast" , "showing disbelief" , "Christian feast" , "the love of God!" , "Christian's love" .)