Gambol like Demi in a short frock (6)
I believe the answer is:
frolic
'gambol' is the definition.
(I know that gambol can be written as frolic)
'demi in a short frock' is the wordplay.
'demi' becomes 'li' (I can't justify this - if you can you should believe this answer much more).
'in' indicates putting letters inside.
'a short' means to remove the last letter.
'frock' with its last letter removed is 'froc'.
'li' going into 'froc' is 'FROLIC'.
'like' is the link.
Can you help me to learn more?
(Other definitions for frolic that I've seen before include "Merrymaking" , "Caper, engage in lively play" , "Caper, cavort" , "Playful action or movement" , "Move in a cheerful and lively way" .)