Cry involves Romeo in fight (5)
I believe the answer is:
brawl
'in fight' is the definition.
(I've seen this before)
'cry involves romeo' is the wordplay.
'cry' becomes 'bawl' (synonyms).
'involves' is an insertion indicator.
'romeo' becomes 'r' (phonetic alphabet: alpha, bravo, charlie etc.).
'bawl' going around 'r' is 'BRAWL'.
(Other definitions for brawl that I've seen before include "Rowdy scuffle" , "Scuffle, unseemly fight" , "squabble" , "Unruly fight" , "Noisy crowd fight" .)