Lots unfortunately mislaid (4)
I believe the answer is:
lost
'mislaid' is the definition.
(similar in meaning)
'lots unfortunately' is the wordplay.
'unfortunately' is an anagram indicator (a bad or unfortunate spelling).
'lots' anagrammed gives 'LOST'.
(Other definitions for lost that I've seen before include "Mislaid or was defeated" , "Suffered defeat" , "Forgotten; misplaced" , "Baffled" , "confused" .)