Fragrant root repellent when peeled slowly at first (5)
I believe the answer is:
orris
'fragrant root' is the definition.
(I've seen this in another clue)
'repellent when peeled slowly at first' is the wordplay.
'repellent' becomes 'horrid' (I've seen this before).
'when peeled' means to look at the middle letters.
'at first' says to take the initial letters.
The middle letters of 'horrid' are 'orri'.
The first letter of 'slowly' is 's'.
'orri'+'s'='ORRIS'
(Other definitions for orris that I've seen before include "Percussion instrument" , "Source of perfume" , "Perfume ingredient from irises" , "Variety of iris" , "Iris with fragrant rhizome" .)