Union supports hardened fellows getting limited selection (3,4)
I believe the answer is:
set menu
'limited selection' is the definition.
I know nothing about this answer so I cannot judge whether this works.
'union supports hardened fellows' is the wordplay.
'union' becomes 'U' (common abbreviation as in Trades Union Congress).
'supports' means one lot of letters go next to another (bottom letters provide a support for the top ones).
'hardened' becomes 'set' (synonyms).
'fellows' becomes 'men' (fellow can mean a man).
'set'+'men'='setmen'
'u' after 'setmen' is 'SET MENU'.
'getting' is the link.
Can you help me to learn more?
(Another definition for set menu that I've seen is " Fixed-price meal with limited options".)