Dwarf cod returned? (3)
I believe the answer is:
doc
'dwarf' is the definition.
(one of the seven)
'cod returned?' is the wordplay.
'returned?' is a reversal indicator (I've seen 'return' mean this).
'cod' in reverse letter order is 'DOC'.
(Other definitions for doc that I've seen before include "Physician (colloq.)" , "bones" , "Holliday (in 17 24)" , "Main dish" , "scaled-down version of GP" .)