Most intimate undies finally put in wardrobe (7)
I believe the answer is:
closest
'most intimate' is the definition.
('close' can be similar in meaning to 'intimate')
'undies finally put in wardrobe' is the wordplay.
'finally' says to take the final letters.
'put in' indicates putting letters inside.
'wardrobe' becomes 'closet' ('closet' can be a synonym of 'wardrobe').
The last letter of 'undies' is 's'.
's' placed within 'closet' is 'CLOSEST'.
(Other definitions for closest that I've seen before include "Superlatively dense" , "Most secretive" , "Most intimate" , "Nearest or meanest" , "Most stuffy" .)