Do but shuffle with uncertainty (5)
I believe the answer is:
doubt
'uncertainty' is the definition.
('doubt' can be a synonym of 'uncertainty')
'do but shuffle' is the wordplay.
'shuffle' is an anagram indicator.
'but' anagrammed gives 'ubt'.
'do'+'ubt'='DOUBT'
'with' is the link.
(Other definitions for doubt that I've seen before include "Misgiving" , "Feel uncertain about" , "Question the truth or accuracy of" , "Disbelieve (someone)" , "Have reservations or be uncertain about" .)