Demolish large new English comprehensive (7)
I believe the answer is:
Here is my best explanation:
'comprehensive' is the definition.
('general' can be similar in meaning to 'comprehensive')
'demolish large new english' is the wordplay.
'demolish' is an anagram indicator.
'new' becomes 'n'.
'english' becomes 'e' (abbreviation).
'largene' is an anagram of 'GENERAL'.
(Other definitions for general that I've seen before include "Of wide application", "Opposite of private!", "Usual; officer", "High ranking officer", "Lee perhaps", "top brass", "Sweeping", "Rank; all-inclusive", "Senior army officer" and "Common - army officer".)