Not disheartened by pace being harsh (8)
I believe the answer is:
strident
'harsh' is the definition.
(thesaurus)
'not disheartened by pace' is the wordplay.
'disheartened' means to remove the middle letters.
'by' says to put letters next to each other.
'pace' becomes 'stride' ('stride' can be a synonym of 'pace'**).
'not' with its centre removed is 'nt'.
'nt' after 'stride' is 'STRIDENT'.
'being' is the link.
(Other definitions for strident that I've seen before include "Unpleasantly loud and harsh" , "With a loud, harsh voice" , "giving views forcefully" , "Commanding attention" , "harsh sound" .)