"Think again!" (4)
(Another definition for uhuh that I've seen is " no".)
'think again' is the definition.
('consider' is an answer for 'think' so perhaps 'reconsider' is OK for 'think again')
This is all the clue.
(Other definitions for reconsider that I've seen before include "Think again" , "Ponder further" , "Nice orders ( anag.)" , "Have second thoughts" .)