Loafer may thus deposit an attack (8)
I believe the answer is:
layabout
'loafer' is the definition.
(I know that loafer can be written as layabout)
'deposit an attack' is the wordplay.
'deposit' becomes 'lay' (deposit can mean to lay down or place).
'an' becomes 'a'.
'attack' becomes 'bout' (eg a bout of flu).
'lay'+'a'+'bout'='LAYABOUT'
'may thus' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for layabout that I've seen before include "One doing little work" , "Unemployed person" , "Idler" , "Lazy person" , "wastrel" .)