Make a mess of hairpiece, occasionally sold for sport (6)
I believe the answer is:
tousle
'make a mess of' is the definition.
(tousle can mean to make someone's hair untidy)
'hairpiece occasionally sold for sport' is the wordplay.
I cannot quite see how this works, but
'for' could be 'to' (eg both can mean 'in the opinion of') and 'to' is present in the answer.
This explanation may well be incorrect...
(Other definitions for tousle that I've seen before include "disarray" , "Make hair untidy by ruffling" , "Mess around" , "Ruffle (the hair)" , "Rumple, make untidy as with hair" .)