Announce as unsuitable function of playground (6)
I believe the answer is:
recuse
'announce as unsuitable' is the definition.
(eg recusing a judge from a case)
'function of playground' is the wordplay.
I cannot quite see how this works, but
'function' could be 'use' (synonyms) and 'use' is located in the answer.
'playground' could be 'rec' (I've seen this in other clues) and 'rec' is found in the answer.
No letters remain.
This may be the basis of clue (or it may be nonsense).
(Another definition for recuse that I've seen is " Disqualify oneself as a judge in a case".)