Good! A school for fuel (3)

I believe the answer is:

gas

'for fuel' is the definition.
(gas is a fuel)

'good a school' is the wordplay.
'good' becomes 'g' (abbreviation).
'school' becomes 'S'.
'g'+'a'+'s'='GAS'

(Other definitions for gas that I've seen before include "Empty talk (colloq.)" , "It may be natural" , "Talk profusely" , "Something that is neither solid not liquid" , "See 2" .)

I've seen this clue in the Sydney Morning Herald.

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