One insect or another that will die ultimately (6)
I believe the answer is:
beetle
'one insect' is the definition.
(beetle is a kind of insect)
'another that will die ultimately' is the wordplay.
'another' becomes 'bee' (I can't justify this - if you can you should give a lot more credence to this answer).
'ultimately' indicates one should take the final letters.
The final letters of 'that will die' are 'tle'.
'bee'+'tle'='BEETLE'
'or' acts as a link.
Can you help me to learn more?
(Other definitions for beetle that I've seen before include "Insect with protective forewings" , "... after {STATE = COLORADO] which he'll do for Charlotte" , "Hard-covered insect" , "Type of insect" , "drawing game > has to hurry" .)