Romeo in skimpy beachwear in crowd (6)
I believe the answer is:
throng
'crowd' is the definition.
(I know this)
'romeo in skimpy beachwear' is the wordplay.
'romeo' becomes 'R' (phonetic alphabet: alpha, bravo, charlie etc.).
'in' indicates putting letters inside.
'skimpy beachwear' becomes 'thong' (I've seen this in another clue).
'r' put into 'thong' is 'THRONG'.
'in' acts as a link.
(Other definitions for throng that I've seen before include "Mob" , "Large numbers" , "Dense crowd" , "Densely packed crowd" , "A great crowd of people" .)