Amino acid from Poland not new, surprisingly (1-4)
I believe the answer is:
l-dopa
'amino acid' is the definition.
(I know that L-dopa is a type of dihydroxyphenylalanine)
'poland not new surprisingly' is the wordplay.
'not' suggests deleting specific letters.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'surprisingly' indicates anagramming the letters (a surprising ordering of the letters).
'poland' with 'n' taken out is 'polad'.
'polad' with letters rearranged gives 'L-DOPA'.
'from' is the link.
(Other definitions for l-dopa that I've seen before include "Pal, do use the drug to treat Parkinson's disease" , "Drug used to treat Parkinson's disease" , "Substance used to treat Parkinson's disease" .)