Hothead foolishly rash and abusive (5)
I believe the answer is:
harsh
'abusive' is the definition.
(thesaurus)
'hothead foolishly rash' is the wordplay.
'hothead' becomes 'h' (head letter of 'hot').
'foolishly' is an anagram indicator.
'rash' with letters rearranged gives 'arsh'.
'h'+'arsh'='HARSH'
'and' is the link.
(Other definitions for harsh that I've seen before include "Severe; bleak" , "Draconian" , "Guttural" , "Raucous - austere - bitter" , "Rough and disagreeable, maybe of voice" .)