Servant is left inside and lost (7)
I believe the answer is:
mislaid
'lost' is the definition.
(similar in meaning)
'servant is left inside' is the wordplay.
'servant' becomes 'maid' (maid is a kind of servant).
'left' becomes 'l' (common abbreviation).
'inside' indicates putting letters inside.
'is'+'l'='isl'
'maid' placed around 'isl' is 'MISLAID'.
'and' is the link.
(Other definitions for mislaid that I've seen before include "Temporarily lost" , "not to be found?" .)