Bathroom feature lit up with energy (4)
I believe the answer is:
tile
'bathroom feature' is the definition.
(I've seen this in another clue)
'lit up with energy' is the wordplay.
'up with' indicates an anagram (letters get chucked up).
'energy' becomes 'e' (physics symbol as in E=mc2).
'lit' anagrammed with 'e' can make 'TILE'.
(Other definitions for tile that I've seen before include "Glazed piece of earthenware as for lining walls" , "Flat piece of ceramic" , "Thin slab of fired clay" , "Roofing slab" , "Roofing material" .)