I hurl tucking into stale old arthropod (9)
I believe the answer is:
trilobite
'old arthropod' is the definition.
'trilobite' can be an answer for 'arthropod' (I have seen 'Extinct arthropod ' mean 'trilobite' so perhaps 'arthropod' could also mean 'trilobite'). I am not sure about the 'old' bit.
'i hurl tucking into stale' is the wordplay.
'i hurl' becomes 'lobi' (I can't explain this - if you can you should give a lot more credence to this answer).
'tucking into' means one lot of letters goes inside another.
'stale' becomes 'trite' (I've seen this in another clue).
'lobi' inserted inside 'trite' is 'TRILOBITE'.
Can you help me to learn more?
(Other definitions for trilobite that I've seen before include "old crawler" , "Common marine fossil" , "Fossil arthropod" , "Extinct arthropod" , "find on Lyme Regis beach?" .)