Wild West's lacking in law, judge reflected (5)
I believe the answer is:
feral
'wild' is the definition.
('feral' can be similar in meaning to 'wild')
'west's lacking in law judge reflected' is the wordplay.
'west' becomes 'w' ('W' can be a synonym of 'west').
'lacking in' is a deletion indicator.
'judge' becomes 'ref'.
'reflected' shows that the letters should be reversed in order.
'law' with 'w' removed is 'la'.
'la'+'ref'='laref'
'laref' written backwards gives 'FERAL'.
(Other definitions for feral that I've seen before include "beastly" , "'Savage, wild (5)'" , "Wild but formerly tame" , "Flare up, going wild" , "Flare up, being fierce" .)