Bobby's small coins? (7)
I believe the answer is:
coppers
'coins?' is the definition.
(copper is a kind of coin)
'bobby's small' is the wordplay.
'bobby' becomes 'copper' (I've seen this before).
'small' becomes 's' (abbreviation - e.g. clothes size).
'copper'+'s'='COPPERS'
(Other definitions for coppers that I've seen before include "Old pennies and policemen" , "loose change?" , "Officers" , "change maybe" , "hardly any 11 [LOLLY]" .)