With hesitation decline (6)
I believe the answer is:
wither
'decline' is the definition.
(I've seen this before)
'with hesitation' is the wordplay.
'hesitation' becomes 'er' (sound made while hesitating - um, er).
'with'+'er'='WITHER'
(Other definitions for wither that I've seen before include "Turn dry and shrivelled" , "decline" , "Shrink, shrivel up" , "Become dry and shrivel" , "Dry up, become shrivelled" .)