Energy consumed by huge English fawn (5)
I believe the answer is:
beige
'fawn' is the definition.
(I've seen this before)
'energy consumed by huge english' is the wordplay.
'energy' becomes 'e' (physics symbol as in E=mci).
'consumed by' means one lot of letters goes inside another (inserted letters get consumed).
'huge' becomes 'big' (similar in meaning).
'english' becomes 'e' (abbreviation).
'e' placed within 'big' is 'beig'.
'beig'+'e'='BEIGE'
(Other definitions for beige that I've seen before include "Shade of brown" , "Pale brown" , "Light sandy fawn colour" , "Pale sandy fawn colour" , "Yellowish-brown" .)