In a level and regular way (6)
I believe the answer is:
evenly
'in a level and regular way' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for evenly that I've seen before include "In level way or manner" , "In smooth or level manner" , "Calmly or equitably" , "avoiding hiccups?" , "(Spread) without irregularities" .)