Cross put back nearly damaged element (7)
I believe the answer is:
sulphur
'element' is the definition.
(sulphur is a kind of element)
'cross put back nearly damaged' is the wordplay.
'cross put' becomes 'plus' (I am not sure about this - if you are sure you should believe this answer much more).
'back' shows that the letters should be reversed in order.
'nearly' means to remove the last letter.
'damaged' becomes 'hurt' (similar in meaning).
'plus' written backwards gives 'sulp'.
'hurt' with its last letter removed is 'hur'.
'sulp'+'hur'='SULPHUR'
Can you help me to learn more?
(Other definitions for sulphur that I've seen before include "Highly flammable yellow element" , "Element, atomic no. 16" , "Chemical element" , "Brimstone" , "Chemical used in match heads" .)