London statue painful to put back (4)
I believe the answer is:
eros
'london statue' is the definition.
(statue of Anteros which is often called Eros)
'painful to put back' is the wordplay.
'painful' becomes 'sore' (similar in meaning).
'to put back' shows that the letters should be reversed in order.
'sore' back-to-front is 'EROS'.
(Other definitions for eros that I've seen before include "Arrow shooter" , "Deity" , "Greek name of Cupid" , "Cupid, son of Aphrodite" , "Goddess" .)