Playing polo, chaps save horse some drinks (8)
I believe the answer is:
alcopops
'some drinks' is the definition.
(I've seen this before)
'playing polo chaps save horse' is the wordplay.
'playing' indicates anagramming the letters.
'save' indicates named letters should be taken away (except).
'horse' becomes 'H' (abbreviation as in horse power).
'polo'+'chaps'='polochaps'
'polochaps' with 'h' taken out is 'polocaps'.
'polocaps' anagrammed gives 'ALCOPOPS'.
(Other definitions for alcopops that I've seen before include "Ready-mixed soft drinks with alcohol" , "drunk on these?" , "drinks designed for the young" , "mixed drinks" , "Those packaged like soft drinks, but containing liquor" .)