Cactus in grave you could pick up? (6)
I believe the answer is:
cereus
'cactus in grave' is the definition.
'cereus' can be an answer for 'cactus' (I've seen this before). I am not sure about the 'in grave' bit.
'you could pick up?' is the wordplay.
'you' becomes 'u' (homophones).
'could' becomes 'ceres' (I can't explain this - if you can you should believe this answer much more).
'pick up?' means one lot of letters goes inside another.
'u' inserted inside 'ceres' is 'CEREUS'.
Can you help me to learn more?
(Another definition for cereus that I've seen is " cactus".)