Preserving reputation — which wastrel never can do? (4-6)

'wastrel never can do?' is the definition.
I can't tell whether this defines the answer.

'preserving reputation' is the wordplay.
I cannot really understand how this works, but
'preserving' could be 'saving' (synonyms) and 'saving' is located in the answer.
The remaining letters 'face' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

'which' acts as a link.

Can you help me to learn more?