Hostilities interrupting commercial settlement (5)
I believe the answer is:
'settlement' is the definition.
(I've seen this before)
'hostilities interrupting commercial' is the wordplay.
'hostilities' becomes 'war' (hostilities between two nations).
'interrupting' indicates putting letters inside.
'commercial' becomes 'ad' (abbreviation for advertisement).
'war' going inside 'ad' is 'AWARD'.
(Other definitions for award that I've seen before include "Allotment" , "Decoration" , "They are disinclined to work" , "Judicial decision" , "Arbitrator's decision" .)