Model order for setter perhaps to settle (3)
I believe the answer is:
sit
I believe this is a triple definition!
'model' is the first definition.
(synonyms)
'order for setter perhaps' is the second definition.
(a dog such as a setter might be ordered to 'sit')
'to' acts as a link.
'settle' is the third definition.
(thesaurus)
(Other definitions for sit that I've seen before include "(Of bird) stay on nest" , "Take a chair" , "Take (an examination)" , "Model" , "Rest on one's haunches" .)