He shouldn't have had a haircut (6)

I believe the answer is:
samson
'a haircut' is the definition.
Both the answer and definition are singular nouns.
Maybe you can see an association between them that I can't see?
'he shouldn't have' is the wordplay.
'he' becomes 'Sam'.
'shouldn't have' becomes 'son' (I can't justify this - if you can you should believe this answer much more).
'sam'+'son'='SAMSON'
'had' acts as a link.
Can you help me to learn more?
(Other definitions for samson that I've seen before include "He destroyed temple" , "Strong man of the Bible, laid low by Delilah" , "Israelite leader betrayed by Delilah" , "Masons (anag.)" , "Old Testament strongman (until he lost his hair)" .)
