Decent lamp is damaged in removal (12)
I believe the answer is:
displacement
'removal' is the definition.
(thesaurus)
'decent lamp is damaged' is the wordplay.
'damaged' is an anagram indicator.
'decent'+'lamp'+'is'='decentlampis'
'decentlampis' anagrammed gives 'DISPLACEMENT'.
'in' acts as a link.
(Other definitions for displacement that I've seen before include "Shift in position" , "Measure of ship's size" , "Amount of movement" .)