Unity in company hour before commotion returned (8)
I believe the answer is:
cohesion
'unity' is the definition.
(I've seen this before)
'company hour before commotion returned' is the wordplay.
'company' becomes 'co' (abbreviation).
'hour' becomes 'h'.
'before' means one lot of letters go next to another.
'commotion' becomes 'noise' (I've seen this in another clue).
'returned' says the letters should be written backwards.
'noise' reversed gives 'esion'.
'co'+'h'+'esion'='COHESION'
'in' acts as a link.
(Other definitions for cohesion that I've seen before include "Togetherness" , "logical connection" , "Tendency to stick together" , "Action of forming a united whole" , "unity" .)