Museum exhibit resembling a head of Lenin, strangely (5,7)
I believe the answer is:
elgin marbles
'museum exhibit' is the definition.
'resembling a head of lenin strangely' is the wordplay.
'head of' indicates taking the first letters.
'strangely' is an anagram indicator.
The first letter of 'lenin' is 'l'.
'resembling'+'a'+'l'='resemblingal'
'resemblingal' with letters rearranged gives 'ELGIN MARBLES'.
(Other definitions for elgin marbles that I've seen before include "Sculptures from the Parthenon, held by the British Museum" , "a lot of relief shown in London" , "Statuary from the Parthenon" , "some old stones" , "5th Century BC Greek sculptures brought to England" .)