What does the cryptic crossword clue "Go grey, perhaps, after near death (6)" mean?

The definition is "Go". The wordplay uses an anagram. EN (synonym="EN") + ERGY (synonym="ERGY") = ENERGY; definition: "Go" The answer is ENERGY.

Go grey, perhaps, after near death (6)

Guardian Cryptic #29178 | 2 Down | 2023-09-18 flower