Good man needing a good party (4)
I believe the answer is:
Here is my best explanation:
'party' is the definition.
(stag party is a kind of party)
'good man needing a good' is the subsidiary indication.
'good man' becomes 'st' (**).
'needing' says to put letters next to each other.
'a good' becomes 'ag' (I've seen this in other clues).
(Other definitions for stag that I've seen before include "No women allowed", "Sort of party", "Stock Exchange speculator standing", "in a rut, perhaps?", "Animal - for men only", "Game - speculator", "Horned animal", "animal of the deer family", "Male beast" and "involving men".)