Fed up with hesitation and delay (5)
I believe the answer is:
defer
'delay' is the definition.
(I know that defer is a more specific form of the action delay)
'fed up with hesitation' is the wordplay.
'up' says the letters should be written backwards (in down clue: letters go upwards).
'with' says to put letters next to each other.
'hesitation' becomes 'er' (sound made while hesitating - um, er).
'fed' backwards is 'def'.
'def'+'er'='DEFER'
'and' acts as a link.
(Other definitions for defer that I've seen before include "Hold over, put off" , "Postpone - submit" , "Delay" , "Stay" , "Allow precedence (to)" .)