Boots may be showing lout in a bad light (9)

'boots may be' is the definition.
(boots may be hobnailed)

'lout in a bad light' is the wordplay.
'lout' becomes 'hob' (hob can mean a lout or troublemaker).
'bad' indicates anagramming the letters.
'light' becomes 'led' (I've seen this before).
'in'+'a'='ina'
'ina' with letters rearranged gives 'nai'.
'hob'+'nai'+'led'='HOBNAILED'

'showing' acts as a link.