In no way could my son be an engineer (2,2,5)
I believe the answer is:
by no means
'in no way' is the definition.
(synonyms)
'my son be an engineer' is the wordplay.
'engineer' is an anagram indicator.
'my'+'son'+'be'+'an'='mysonbean'
'mysonbean' is an anagram of 'BY NO MEANS'.
'could' is the link.
(Other definitions for by no means that I've seen before include "Certainly not, perish the thought" , "Certainly not, not in any way" , "Forbids" , "Definitely not" , "Without using any method" .)