Strapping treatment for last skin blemish (8)
I believe the answer is:
stalwart
'strapping' is the definition.
(thesaurus)
'treatment for last skin blemish' is the wordplay.
'treatment for' is an anagram indicator (I've seen this in other clues).
'skin blemish' becomes 'wart' (I've seen this before).
'last' with letters rearranged gives 'stal'.
'stal'+'wart'='STALWART'
(Other definitions for stalwart that I've seen before include "Staunchly faithful" , "Tart laws could be strong and sturdy" , "Staunch supporter" , "Reliable; sturdy" , "Dependable figure" .)