Crossword Genius

Guaranteed details, extra sparse (7)

Ross

I believe the answer is:

surplus

I'm a little stuck... Click here to teach me more about this clue!

'sparse' is the definition.
Both the definition and answer are adjectives. Maybe you can see an association between them that I don't see?

'guaranteed details extra' is the wordplay.
'guaranteed details' becomes 'sur' (I am not sure about this - if you are sure you should believe this answer much more).
'extra' becomes 'plus' (plus can mean more than expected).
'sur'+'plus'='SURPLUS'

Can you help me to learn more?

(Other definitions for surplus that I've seen before include "Extra to requirements" , "superfluity" , "Excess, overstock" , "balance" , "Surfeit" .)

I've seen this clue in the Sydney Morning Herald.
Want a hint initially instead of a full solution? Install my app