Suspend setter for such an expression? (7)
I believe the answer is:
hangdog
'such an expression?' is the definition.
(a hangdog expression is a sad expression)
'suspend setter' is the wordplay.
'suspend' becomes 'hang' (to hang is to suspend from something).
'setter' becomes 'dog' (a setter is a type of dog).
'hang'+'dog'='HANGDOG'
'for' is the link.
(Other definitions for hangdog that I've seen before include "Shamefaced like suspended canine?" , "Suspend canine with shamefaced look" , "Cowed, furtive" , "Looking guiltily dejected" , "With a guilty look" .)