List of soldiers joining unit at the start (4)
I believe the answer is:
menu
'list' is the definition.
(list of dishes)
'soldiers joining unit at the start' is the wordplay.
'soldiers' becomes 'men' (men can mean a group of soldiers).
'joining' means one lot of letters go next to another.
'at the start' says to take the initial letters.
The initial letter of 'unit' is 'u'.
'men'+'u'='MENU'
'of' is the link.
(Other definitions for menu that I've seen before include "List of fare" , "List of options" , "Choice of dishes" , "Bill of fare" , "List of food items on offer" .)