Feeling shown by men too upset about one (7)
I believe the answer is:
emotion
'feeling' is the definition.
(I know that emotion is a type of feeling)
'men too upset about one' is the wordplay.
'upset' indicates anagramming the letters.
'about' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'men'+'too'='mentoo'
'mentoo' with letters rearranged gives 'emoton'.
'emoton' placed around 'i' is 'EMOTION'.
'shown by' is the link.
(Other definitions for emotion that I've seen before include "Agitation of mind" , "Passion" , "Anger, perhaps" , "Mental agitation" , "Strong feeling, love or jealousy" .)