Fool! One very involved with environment's beginning to gush (when going by this?) (7,3)
I believe the answer is:
private jet
'going by this?' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'fool one very involved with environment's beginning to gush when' is the wordplay.
I cannot really see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found in the answer.
'very' could be 'v' (abbreviation) and 'v' is present in the answer.
'fool' could be 'prat' and 'prat' is located in the remaining letters.
'gush' could be 'jet' (synonyms) and 'jet' is located in the answer.
'when' could be 'e' (I've seen this in other clues) and 'e' is located in the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).