What does the cryptic crossword clue "Greener, VAT-exempt, houses weakened (8)" mean?

The definition is "weakened". The wordplay uses a hidden word. hidden in "Greener, VAT-exempt," The answer is ENERVATE.

Greener, VAT-exempt, houses weakened (8)

Guardian Cryptic #27278 | 26 Across | 2017-08-17 flower