Can Penny hold back? (8)
I believe the answer is:
preserve
'can' is the definition.
(preserve in a can)
'penny hold back?' is the wordplay.
'penny' becomes 'p' (short for pence).
'hold back?' becomes 'reserve' (reserve can mean to keep or hold something back).
'p'+'reserve'='PRESERVE'
(Other definitions for preserve that I've seen before include "Maintain - jam" , "Area of activity" , "Keep alive; jam" , "Keep from decay, corpse or food" , "Maintain in unaltered condition" .)