Blow last of pimiento to make relish (5)
I believe the answer is:
gusto
'relish' is the definition.
('gusto' can be a synonym of 'relish')
'blow last of pimiento' is the wordplay.
'blow' becomes 'gust' ('gust' can be a synonym of 'blow'**).
'last of' says to take the final letters.
The final letter of 'pimiento' is 'o'.
'gust'+'o'='GUSTO'
'to make' is the link.
(Other definitions for gusto that I've seen before include "Great enjoyment in doing something" , "Showing zest" , "Verve, zest" , "Zest and enjoyment in doing something" , "Obvious enthusiasm" .)