Pull back, having left a track when retreating -- that's harsh (8)
I believe the answer is:
guttural
'harsh' is the definition.
(thesaurus)
'pull back having left a track when retreating' is the wordplay.
'pull' becomes 'tug' (to tug something is to pull it).
'back' shows that the letters should be reversed in order.
'having left' becomes 'la' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'a track' becomes 'rut' (rut is a kind of track).
'when retreating' says the letters should be written backwards.
'tug' in reverse letter order is 'gut'.
'la'+'rut'='larut'
'larut' in reverse letter order is 'tural'.
'gut'+'tural'='GUTTURAL'
'that's' is the link.
Can you help me to learn more?
(Other definitions for guttural that I've seen before include "Type of speech" , "(Of sound) produced in the throat" , "Articulated in the throat" , "In phonetics, pronounced via throat" , "Harsh-sounding or throaty, like some languages" .)