Spot Liberal out of fashion (4)
I believe the answer is:
stye
'spot' is the definition.
(I have seen 'nasty spot' mean 'stye' so perhaps 'spot' could also mean 'stye')
'liberal out of fashion' is the wordplay.
'liberal' becomes 'l' (abbreviation).
'out of' suggests deleting specific letters ('out of' can mean no longer having).
'fashion' becomes 'style' (synonyms).
'style' with 'l' taken away is 'STYE'.
(Other definitions for stye that I've seen before include "Observer's problem" , "Ocular inflammation" , "Swelling near the eye" , "Eyelid sore" , "dump" .)