Short cone and tall cone share an end (8)
I believe the answer is:
conspire
'end' is the definition.
Although both the answer and definition are verbs in their base form, I can't understand how they can define each other.
'short cone and tall cone share' is the wordplay.
'short' means to remove the last letter.
'and' says to put letters next to each other.
'tall cone share' becomes 'spire' (I can't justify this - if you can you should believe this answer much more).
'cone' with its last letter taken away is 'con'.
'con'+'spire'='CONSPIRE'
'an' is the link.
Can you help me to learn more?
(Other definitions for conspire that I've seen before include "'Plot, connive (8)'" , "Plot together - on prices (anag)" , "So prince is given to plan secretly with others" , "Secretly plan together" , "Collude" .)