Be there at the first conclusion (6)
I believe the answer is:
attend
'be' is the definition.
(I know that attend has the is a more specific form of the action be)
'there at the first conclusion' is the wordplay.
'there' becomes 't' (this could be a standard abbreviation which I don't know about).
'the first' says to put letters next to each other.
'conclusion' becomes 'end' (something's conclusion is its end).
't' put after 'at' is 'att'.
'att'+'end'='ATTEND'
Can you help me to learn more?
(Other definitions for attend that I've seen before include "Concentrate carefully" , "take heed" , "visit" , "Be present at, say meeting" , "Follow" .)