Frolic on adult beach in Spain (5)
I believe the answer is:
playa
'beach in spain' is the definition.
'playa' can be an answer for 'beach' (I have seen 'Spanish beach ' mean 'playa' so perhaps 'beach' could also mean 'playa'). I am not certain of the 'in spain' bit.
'frolic on adult' is the wordplay.
'frolic' becomes 'play' (synonyms).
'on' is a charade indicator (letters next to each other) (in a down clue, letters appear on others).
'adult' becomes 'a' (abbreviation).
'play'+'a'='PLAYA'
Can you help me to learn more?
(Other definitions for playa that I've seen before include "piece of land liable to flood" , "Spanish beach" , "bed in Spain" , "Expanse of dry land" , "lake after rainfall" .)