Frivolously, soldier starts to dress down the Italian on the fourth of July (7)
I believe the answer is:
giddily
'frivolously' is the definition.
(I've seen this before)
'soldier starts to dress down the italian on the fourth of july' is the wordplay.
'soldier' becomes 'GI' (GI can mean a US soldier).
'starts to' suggests taking the first letters.
'the italian' becomes 'il' ('the' in Italian).
'on' says to put letters next to each other.
'the fourth of july' becomes 'y' (4th letter of 'july').
The first letters of 'dress down' is 'dd'.
'gi'+'dd'+'il'+'y'='GIDDILY'
(Other definitions for giddily that I've seen before include "Dizzily" , "frivolously" .)