First Lady stuffs this in trousers (7)
I believe the answer is:
thieves
'trousers' is the definition.
(trouser can informally mean to steal)
'first lady stuffs this' is the wordplay.
'first lady' becomes 'eve' (I've seen this before).
'stuffs' is an insertion indicator.
'eve' put into 'this' is 'THIEVES'.
'in' is the link.
(Other definitions for thieves that I've seen before include "eg Pick-pockets" , "Crooks" , "Stealers" , "they have taking ways" , "Robbers" .)