Romeo and other Montague, initially aimless (6)
I believe the answer is:
random
'aimless' is the definition.
(thesaurus)
'romeo and other montague initially' is the wordplay.
'romeo' becomes 'R' (phonetic alphabet: alpha, bravo, charlie etc.).
'initially' says to take the initial letters.
The first letters of 'other montague' is 'om'.
'r'+'and'+'om'='RANDOM'
(Other definitions for random that I've seen before include "'Haphazard, irregular (6)'" , "Happening by chance, haphazard" , "Governed by chance" , "Done or taken without particular aim" , "without any plan" .)