Grass was slippery on road (5)
I believe the answer is:
sward
'grass' is the definition.
(literary term for grass)
'was slippery on road' is the wordplay.
'slippery' indicates an anagram (I've seen this in other clues).
'on' means one lot of letters go next to another.
'road' becomes 'rd' (abbreviation).
'was' is an anagram of 'swa'.
'swa'+'rd'='SWARD'
(Other definitions for sward that I've seen before include "Ground covered by a mat of grass and grass roots" , "Area of short grass" , "Stretch of turf or grass" , "Expanse of grass" , "Grassy area" .)