Play around in Leatherhead, obviously (7)
I believe the answer is:
plainly
'obviously' is the definition.
(I know that obviously can be written as plainly)
'play around in leatherhead' is the wordplay.
'around' is an insertion indicator.
'leatherhead' becomes 'l' (head letter of 'leather').
'in'+'l'='inl'
'play' enclosing 'inl' is 'PLAINLY'.
(Other definitions for plainly that I've seen before include "... without embellishment" , "Clearly" , "In unconcealed fashion" , "obviously" , "Simply" .)