Remember playground in its entirety (6)
I believe the answer is:
recall
'remember' is the definition.
(to recall something is to remember it)
'playground in its entirety' is the wordplay.
I cannot really see how this works, but
'playground' could be 'rec' (short for recreation ground) and 'rec' is found in the answer.
'entirety' could be 'all' (I've seen this in another clue) and 'all' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for recall that I've seen before include "Summon back, perhaps to mind" , "Summon back as to memory" , "Request the return of a defective product" , "Hark back" , "Get back" .)