Something that happens with flat tyre initially (5)
I believe the answer is:
event
'something that happens' is the definition.
(I've seen this before)
'with flat tyre initially' is the wordplay.
'with' says to put letters next to each other.
'flat' becomes 'even' (level).
'initially' says to take the initial letters.
The first letter of 'tyre' is 't'.
'even'+'t' is 'EVENT'.
(Other definitions for event that I've seen before include "pole vault maybe" , "celebration?" , "What will happen" , "important" , "match" .)