Look at commercial responsibility (4)
I believe the answer is:
load
'responsibility' is the definition.
(thesaurus)
'look at commercial' is the wordplay.
'look' becomes 'lo'.
'at' says to put letters next to each other.
'commercial' becomes 'ad'.
'lo'+'ad'='LOAD'
(Other definitions for load that I've seen before include "Weight to be transported" , "Great quantity" , "pack" , "Weight, source of pressure" , "Burden, onus" .)