Holding back, washes it antiseptically in part (8)
I believe the answer is:
hesitant
'holding back' is the definition.
(to hold back is to hesitate)
'washes it antiseptically in part' is the wordplay.
'in part' indicates a hidden word.
'HESITANT' can be found hidden inside 'washes it antiseptically'.
(Other definitions for hesitant that I've seen before include "Slow to speak or act" , "Reluctant (to speak, act)" , "Reluctant, feeling indecision" , "Expressing doubts" , "Uncertain, nervous" .)