Sport is primarily entertainment inspired by conflict (4)
I believe the answer is:
wear
'sport' is the definition.
(thesaurus)
'primarily entertainment inspired by conflict' is the wordplay.
'primarily' suggests taking the first letters.
'inspired by' indicates putting letters inside.
'conflict' becomes 'war' (war is a kind of conflict).
The initial letter of 'entertainment' is 'e'.
'e' placed into 'war' is 'WEAR'.
'is' acts as a link.
(Other definitions for wear that I've seen before include "Become damaged by use" , "Accept" , "Sunderland river" , "Northern flower" , "Northern runner" .)