Romeo possibly sleeping around is natural (6)
I believe the answer is:
inbred
'natural' is the definition.
(similar in meaning)
'romeo possibly sleeping around is' is the wordplay.
I cannot quite see how this works, but
'romeo' could be 'r' (phonetic alphabet: alpha, bravo, charlie etc.) and 'r' is found within the answer.
'is' could be 'be' and 'be' is located in the remaining letters.
The remaining letters 'ind' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for inbred that I've seen before include "Inborn" , "4 across" , "from a restricted gene pool?" , "Existing from birth, derived from parentage" , "Present by nature" .)