Argue no cement that's mixed can provide support (13)
I believe the answer is:
encouragement
'support' is the definition.
(I've seen this before)
'argue no cement that's mixed' is the wordplay.
'that's mixed' is an anagram indicator.
'argue'+'no'+'cement'='arguenocement'
'arguenocement' is an anagram of 'ENCOURAGEMENT'.
'can provide' is the link.
(Other definitions for encouragement that I've seen before include "Shot in the arm" , "Advocacy" , "Something that heartens" , "Act of spurring on" , "Persuasion" .)