Crossword Genius

A number may be lost by certain units (5)

Ross

I believe the answer is:

volts

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

'certain units' is the definition.
'volts' can be an answer for 'units' (volt is a kind of unit). I am unsure of the 'certain' bit.

'a number may be lost by' is the wordplay.
'a number' becomes 'v' (V is an example).
'may be' is an anagram indicator.
'by' is a charade indicator (letters next to each other).
'lost' anagrammed gives 'olts'.
'v'+'olts'='VOLTS'

Can you help me to learn more?

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