Tear apart Romeo's flower (5)
I believe the answer is:
river
'flower' is the definition.
(A river flows and is therefore a flower)
'tear apart romeo's' is the wordplay.
'tear apart' becomes 'rive' (I've seen this in another clue).
'romeo' becomes 'R' (phonetic alphabet: alpha, bravo, charlie etc.).
'rive'+'r'='RIVER'
(Other definitions for river that I've seen before include "Eg, Amazon" , "Tees, perhaps" , "eg Aire" , "course of 1d [ADVENTURE]" , "One splits" .)