Abrasive having advantage over the timid? (6)
I believe the answer is:
pumice
'abrasive' is the definition.
(I've seen this before)
'having advantage over the timid?' is the wordplay.
'having advantage' becomes 'up' (the team in the lead is described as 'up').
'over' says the letters should be written in reverse.
'the timid?' becomes 'mice' (mice are famously timid).
'up' reversed gives 'pu'.
'pu'+'mice'='PUMICE'
(Other definitions for pumice that I've seen before include "Lava stone" , "Volcanic-rock scourer" , "Light porous stone used as polishing powder" , "Solidified lava used as an abrasive" , "Mineral" .)