Masculinity of Scot, having his moment (8)
I believe the answer is:
machismo
'masculinity' is the definition.
(machismo is a kind of masculinity)
'scot having his moment' is the wordplay.
'scot' becomes 'mac' (many Scottish surnames begin with Mac).
'having' says to put letters next to each other.
'moment' becomes 'mo' (as in 'just a mo').
'mac'+'his'+'mo'='MACHISMO'
'of' is the link.
(Other definitions for machismo that I've seen before include "Aggressive virility" , "Cult of masculinity" , "Agressive masculine pride" , "Cult of virility" , "Exaggerated sense of manliness" .)