Instrument in amazing article on processed signal (3,7)
I believe the answer is:
cor anglais
'instrument' is the definition.
(cor anglais is a kind of instrument)
'amazing article on processed signal' is the wordplay.
'amazing' becomes 'cor' (both are expressions of surprise**).
'article' becomes 'a' (indefinite article).
'on' says to put letters next to each other.
'processed' is an anagram indicator.
'signal' anagrammed gives 'nglais'.
'cor'+'a'+'nglais'='COR ANGLAIS'
'in' acts as a link.
(Other definitions for cor anglais that I've seen before include "alto member of family" , "Woodwind instrument" , "horn?" , "MUSICAL INSTRUMENT" , "belonging to a broken-down 27 [CARTHORSE]" .)