Roughness of a warrior going around island, returning to headland (12)

'roughness' is the definition.
(abrasiveness is a kind of roughness)

'a warrior going around island returning to headland' is the wordplay.
'warrior' becomes 'brave' (brave is a kind of warrior).
'going around' is an insertion indicator.
'island' becomes 'is' (geographical abbreviation).
'returning' shows that the letters should be reversed in order.
'to headland' becomes 'ness' (both can mean a promontory).
'is' written backwards gives 'si'.
'brave' enclosing 'si' is 'brasive'.
'a'+'brasive'+'ness'='ABRASIVENESS'

'of' is the link.