Eats quickly? Not so fast, picking up fine when it's brought back (5)

'eats quickly?' is the definition.

'not so fast picking up fine when it's brought back' is the wordplay.
'not so fast' becomes 'slow'.
'picking up' means one lot of letters goes inside another.
'fine' becomes 'f' (abbreviation).
'when it's brought back' says the letters should be written in reverse.
'slow' enclosing 'f' is 'sflow'.
'sflow' in reverse letter order is 'WOLFS'.