Possibly play about half of it properly (5)
I believe the answer is:
aptly
'properly' is the definition.
(thesaurus)
'possibly play about half of it' is the wordplay.
'possibly' is an anagram indicator.
'about' is an insertion indicator.
'half of' means to take half the letters.
'play' with letters rearranged gives 'aply'.
'it' with half the letters taken is 't'.
'aply' going around 't' is 'APTLY'.
(Other definitions for aptly that I've seen before include "Appropriately" , "In suitable form" , "In a suitable manner" , "as is fitting" , "Fittingly" .)