Exploit dwarf (5)
I believe the answer is:
stunt
This clue is a double definition.
'exploit' is the first definition.
(I know that stunt is a type of exploit)
'dwarf' is the second definition.
(I know that dwarf is a more specific form of the action stunt)
(Other definitions for stunt that I've seen before include "Inhibit - exploit" , "Action to gain attention, sometimes dangerous" , "Hinder the growth of" , "Restrict growth" , "Daring act - cause not to develop" .)